ci(maven): Use GitHub cache action v4.

.github/workflows/maven.yml

@@ -42,7 +42,7 @@ jobs:
         # Add yarn path to GITHUB_PATH so that global package is executable.
         echo "$(yarn global bin)" >> $GITHUB_PATH
     - name: Setup Maven Cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       id: cache
       with:
         path: ~/.m2