deps: update dependency com.google.code.gson:gson to v2.12.1 (#3599)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [com.google.code.gson:gson](https://redirect.github.com/google/gson) |
`2.12.0` -> `2.12.1` |
[![age](https://developer.mend.io/api/mc/badges/age/maven/com.google.code.gson:gson/2.12.1?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/maven/com.google.code.gson:gson/2.12.1?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![passing](https://developer.mend.io/api/mc/badges/compatibility/maven/com.google.code.gson:gson/2.12.0/2.12.1?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/maven/com.google.code.gson:gson/2.12.0/2.12.1?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

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Author: renovate-bot

gapic-generator-java-pom-parent/pom.xml

@@ -29,7 +29,7 @@
     <grpc.version>1.69.0</grpc.version>
     <google.auth.version>1.31.0</google.auth.version>
     <google.http-client.version>1.45.3</google.http-client.version>
-    <gson.version>2.12.0</gson.version>
+    <gson.version>2.12.1</gson.version>
     <guava.version>33.4.0-jre</guava.version>
     <protobuf.version>3.25.5</protobuf.version>
     <opentelemetry.version>1.46.0</opentelemetry.version>