chore: update actions/cache to v4

Author: svenjacobs

Diff for: .github/actions/gradle-cache/action.yml

@@ -4,7 +4,7 @@ description: 'Setup Gradle cache'
 runs:
   using: 'composite'
   steps:
-    - uses: actions/cache@v3
+    - uses: actions/cache@v4
       with:
         path: ~/.gradle/caches
         key: ${{ runner.os }}-gradle-${{ hashFiles('gradle/libs.versions.toml') }}