Bump actions/checkout from 6 to 7 (#171)

Author: dependabot[bot]

.github/workflows/gradle.yml

@@ -20,7 +20,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - name: Set up JDK 21
         uses: actions/setup-java@v5
         with: