chore(main): release 2.5.6-SNAPSHOT (#741)

:robot: I have created a release *beep* *boop*
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### Updating meta-information for bleeding-edge SNAPSHOT release.

---
This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).
diff --git a/java-core/google-cloud-core-bom/pom.xml b/java-core/google-cloud-core-bom/pom.xml
index 8de1311..765eaaa 100644
--- a/java-core/google-cloud-core-bom/pom.xml
+++ b/java-core/google-cloud-core-bom/pom.xml
@@ -3,7 +3,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-core-bom</artifactId>
-  <version>2.5.5</version><!-- {x-version-update:google-cloud-core:current} -->
+  <version>2.5.6-SNAPSHOT</version><!-- {x-version-update:google-cloud-core:current} -->
   <packaging>pom</packaging>
   <parent>
     <groupId>com.google.cloud</groupId>
@@ -63,22 +63,22 @@
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-core</artifactId>
-        <version>2.5.5</version><!-- {x-version-update:google-cloud-core:current} -->
+        <version>2.5.6-SNAPSHOT</version><!-- {x-version-update:google-cloud-core:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-core-grpc</artifactId>
-        <version>2.5.5</version><!-- {x-version-update:google-cloud-core:current} -->
+        <version>2.5.6-SNAPSHOT</version><!-- {x-version-update:google-cloud-core:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-core-http</artifactId>
-        <version>2.5.5</version><!-- {x-version-update:google-cloud-core:current} -->
+        <version>2.5.6-SNAPSHOT</version><!-- {x-version-update:google-cloud-core:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>native-image-support</artifactId>
-        <version>0.12.5</version><!-- {x-version-update:native-image-support:current} -->
+        <version>0.12.6-SNAPSHOT</version><!-- {x-version-update:native-image-support:current} -->
       </dependency>
     </dependencies>
   </dependencyManagement>
diff --git a/java-core/google-cloud-core-grpc/pom.xml b/java-core/google-cloud-core-grpc/pom.xml
index a9cf8ff..00f11af 100644
--- a/java-core/google-cloud-core-grpc/pom.xml
+++ b/java-core/google-cloud-core-grpc/pom.xml
@@ -3,7 +3,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-core-grpc</artifactId>
-  <version>2.5.5</version><!-- {x-version-update:google-cloud-core:current} -->
+  <version>2.5.6-SNAPSHOT</version><!-- {x-version-update:google-cloud-core:current} -->
   <packaging>jar</packaging>
   <name>Google Cloud Core gRPC</name>
   <url>https://github.com/googleapis/java-core</url>
@@ -13,7 +13,7 @@
   <parent>
     <groupId>com.google.cloud</groupId>
     <artifactId>google-cloud-core-parent</artifactId>
-    <version>2.5.5</version><!-- {x-version-update:google-cloud-core:current} -->
+    <version>2.5.6-SNAPSHOT</version><!-- {x-version-update:google-cloud-core:current} -->
   </parent>
   <properties>
     <site.installationModule>google-cloud-core-grpc</site.installationModule>
diff --git a/java-core/google-cloud-core-http/pom.xml b/java-core/google-cloud-core-http/pom.xml
index 3e061e2..4e08c99 100644
--- a/java-core/google-cloud-core-http/pom.xml
+++ b/java-core/google-cloud-core-http/pom.xml
@@ -3,7 +3,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-core-http</artifactId>
-  <version>2.5.5</version><!-- {x-version-update:google-cloud-core:current} -->
+  <version>2.5.6-SNAPSHOT</version><!-- {x-version-update:google-cloud-core:current} -->
   <packaging>jar</packaging>
   <name>Google Cloud Core HTTP</name>
   <url>https://github.com/googleapis/java-core</url>
@@ -13,7 +13,7 @@
   <parent>
     <groupId>com.google.cloud</groupId>
     <artifactId>google-cloud-core-parent</artifactId>
-    <version>2.5.5</version><!-- {x-version-update:google-cloud-core:current} -->
+    <version>2.5.6-SNAPSHOT</version><!-- {x-version-update:google-cloud-core:current} -->
   </parent>
   <properties>
     <site.installationModule>google-cloud-core-http</site.installationModule>
diff --git a/java-core/google-cloud-core/pom.xml b/java-core/google-cloud-core/pom.xml
index 58708c8..6456143 100644
--- a/java-core/google-cloud-core/pom.xml
+++ b/java-core/google-cloud-core/pom.xml
@@ -3,7 +3,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-core</artifactId>
-  <version>2.5.5</version><!-- {x-version-update:google-cloud-core:current} -->
+  <version>2.5.6-SNAPSHOT</version><!-- {x-version-update:google-cloud-core:current} -->
   <packaging>jar</packaging>
   <name>Google Cloud Core</name>
   <url>https://github.com/googleapis/java-core</url>
@@ -13,7 +13,7 @@
   <parent>
     <groupId>com.google.cloud</groupId>
     <artifactId>google-cloud-core-parent</artifactId>
-    <version>2.5.5</version><!-- {x-version-update:google-cloud-core:current} -->
+    <version>2.5.6-SNAPSHOT</version><!-- {x-version-update:google-cloud-core:current} -->
   </parent>
   <properties>
     <site.installationModule>google-cloud-core</site.installationModule>
diff --git a/java-core/native-image-support/pom.xml b/java-core/native-image-support/pom.xml
index 98b19ac..3e293de 100644
--- a/java-core/native-image-support/pom.xml
+++ b/java-core/native-image-support/pom.xml
@@ -7,13 +7,13 @@
   <name>Google Cloud Native Image Support</name>
   <groupId>com.google.cloud</groupId>
   <artifactId>native-image-support</artifactId>
-  <version>0.12.5</version><!-- {x-version-update:native-image-support:current} -->
+  <version>0.12.6-SNAPSHOT</version><!-- {x-version-update:native-image-support:current} -->
   <packaging>jar</packaging>
 
   <parent>
     <artifactId>google-cloud-core-parent</artifactId>
     <groupId>com.google.cloud</groupId>
-    <version>2.5.5</version> <!-- {x-version-update:google-cloud-core:current} -->
+    <version>2.5.6-SNAPSHOT</version> <!-- {x-version-update:google-cloud-core:current} -->
   </parent>
 
   <description>
diff --git a/java-core/pom.xml b/java-core/pom.xml
index d561439..e57e666 100644
--- a/java-core/pom.xml
+++ b/java-core/pom.xml
@@ -4,7 +4,7 @@
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-core-parent</artifactId>
   <packaging>pom</packaging>
-  <version>2.5.5</version><!-- {x-version-update:google-cloud-core:current} -->
+  <version>2.5.6-SNAPSHOT</version><!-- {x-version-update:google-cloud-core:current} -->
   <name>Google Cloud Core Parent</name>
   <url>https://github.com/googleapis/java-core</url>
   <description>
diff --git a/java-core/versions.txt b/java-core/versions.txt
index 085bce8..871686f 100644
--- a/java-core/versions.txt
+++ b/java-core/versions.txt
@@ -1,5 +1,5 @@
 # Format:
 # module:released-version:current-version
 
-google-cloud-core:2.5.5:2.5.5
-native-image-support:0.12.5:0.12.5
\ No newline at end of file
+google-cloud-core:2.5.5:2.5.6-SNAPSHOT
+native-image-support:0.12.5:0.12.6-SNAPSHOT
\ No newline at end of file