Move hardcoded library versions into libs.versions.toml

Change-Id: I347aa2837599878c747c6808700484ae7a95b8ef
diff --git a/datastore/datastore-preferences-core/build.gradle b/datastore/datastore-preferences-core/build.gradle
index e70344bf..f5916e5 100644
--- a/datastore/datastore-preferences-core/build.gradle
+++ b/datastore/datastore-preferences-core/build.gradle
@@ -71,9 +71,8 @@
             nativeMain {
                 dependsOn(commonMain)
                 dependencies {
-                    //TODO(paulmalolepsy) Moving to libs.version.toml in next commit.
-                    implementation("org.jetbrains.kotlinx:kotlinx-serialization-core:1.3.3")
-                    implementation("org.jetbrains.kotlinx:kotlinx-serialization-protobuf:1.3.3")
+                    implementation(libs.kotlinSerializationCore)
+                    implementation(libs.kotlinSerializationProtobuf)
                 }
             }
 
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index f5d0695..e842140 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -34,6 +34,7 @@
 kotlinNative = "1.7.10"
 kotlinCompileTesting = "1.4.1"
 kotlinCoroutines = "1.6.1"
+kotlinSerialization = "1.3.3"
 ksp = "1.7.10-1.0.6"
 ktlint = "0.46.0-20220520.192227-74"
 leakcanary = "2.8.1"
@@ -121,6 +122,8 @@
 kotlinDaemonEmbeddable = { module = "org.jetbrains.kotlin:kotlin-daemon-embeddable", version.ref = "kotlin" }
 kotlinKlibCommonizer = { module = "org.jetbrains.kotlin:kotlin-klib-commonizer", version.ref = "kotlin" }
 kotlinMetadataJvm = { module = "org.jetbrains.kotlinx:kotlinx-metadata-jvm", version = "0.5.0" }
+kotlinSerializationCore = { module = "org.jetbrains.kotlinx:kotlinx-serialization-core", version.ref = "kotlinSerialization" }
+kotlinSerializationProtobuf = { module = "org.jetbrains.kotlinx:kotlinx-serialization-protobuf", version.ref = "kotlinSerialization" }
 kotlinStdlib = { module = "org.jetbrains.kotlin:kotlin-stdlib", version.ref = "kotlin" }
 kotlinStdlibCommon = { module = "org.jetbrains.kotlin:kotlin-stdlib-common", version.ref = "kotlin" }
 kotlinStdlibJdk8 = { module = "org.jetbrains.kotlin:kotlin-stdlib-jdk8", version.ref = "kotlin" }