Update peter-evans/create-pull-request action to v8

Author: renovate[bot]

.github/workflows/update-gradle-versions.yml

@@ -31,7 +31,7 @@ jobs:
         run: ./gradlew :project-generator:test :cli:test
 
       - name: Create pull request
-        uses: peter-evans/create-pull-request@v7
+        uses: peter-evans/create-pull-request@v8
         with:
           commit-message: Update bundled Gradle versions
           title: Update bundled Gradle versions