update actions/cache to v4

Author: jochen-testingbot

.github/workflows/release.yml

@@ -20,7 +20,7 @@ jobs:
         distribution: 'adopt'
 
     - name: Cache Maven dependencies
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: ~/.m2/repository
         key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}