chore: fix ci deprecations, bump actions/cache 3 => 4 (#160)

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') }}