update cache to fix broken actions?

Author: vonnieda

.github/workflows/build.yml

@@ -31,7 +31,7 @@ jobs:
           gpg-passphrase: MAVEN_GPG_PASSPHRASE
 
       - name: Cache maven packages
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: ~/.m2/repository
           key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}