Migrate release notification to Google Chat

**Auto-cherry-pick to `3.2.x` & `3.1.x`**

Author: artembilan

.github/workflows/release.yml

@@ -27,4 +27,4 @@ jobs:
       OSSRH_STAGING_PROFILE_NAME: ${{ secrets.OSSRH_STAGING_PROFILE_NAME }}
       GPG_PASSPHRASE: ${{ secrets.GPG_PASSPHRASE }}
       GPG_PRIVATE_KEY: ${{ secrets.GPG_PRIVATE_KEY }}
-      SPRING_RELEASE_SLACK_WEBHOOK_URL: ${{ secrets.SPRING_RELEASE_SLACK_WEBHOOK_URL }}
+      SPRING_RELEASE_CHAT_WEBHOOK_URL: ${{ secrets.SPRING_RELEASE_GCHAT_WEBHOOK_URL }}