chore: fix ci deprecations, bump actions/cache 3 => 4 (#80)

Co-authored-by: Christopher Georg <[email protected]>

Author: Chris53897

.github/workflows/ci.yaml

@@ -44,7 +44,7 @@ jobs:
               run: echo "dir=$(composer config cache-files-dir)" >> $GITHUB_OUTPUT
 
             - name: Cache dependencies
-              uses: actions/cache@v3
+              uses: actions/cache@v4
               with:
                   path: ${{ steps.composer-cache.outputs.dir }}
                   key: ${{ matrix.php }}-composer-${{ hashFiles('**/composer.json') }}