Migrate to using = for property setting

Gradle has deprecated `compileSdk 35` style syntax in
Gradle 8.12, in preparation for that upgrade, fix up the violations
in androidx build.gradle files

Test: ./gradlew bOS --dry-run -> https://ge.androidx.dev/s/bqs4fmehxdqzs/deprecations
      and after -> https://ge.androidx.dev/s/nvc7s5bdfpuaa/deprecations
Change-Id: Ic4787d46f40e3856e5f0fa1e3c0a63e3dddc2108
diff --git a/testutils/testutils-mockito/build.gradle b/testutils/testutils-mockito/build.gradle
index 8550ce9..174351dc 100644
--- a/testutils/testutils-mockito/build.gradle
+++ b/testutils/testutils-mockito/build.gradle
@@ -39,7 +39,7 @@
     lintOptions {
         disable "InvalidPackage" // Lint is unhappy about java.lang.instrument package
     }
-    namespace "androidx.testutils.mockito"
+    namespace = "androidx.testutils.mockito"
 }
 
 androidx {