CI: update to newest version of gradle wrapper validation

The v3 version is quite old and seems not to work anymore. We get ETIMEDOUT errors when using it.

Author: FSchumacher

.github/workflows/gradle-wrapper-validation.yml

@@ -7,4 +7,4 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v5
-      - uses: gradle/wrapper-validation-action@v3
+      - uses: gradle/wrapper-validation-action@v5