Update cache action

Author: dpanta94

.github/workflows/tests-php.yml

@@ -32,7 +32,7 @@ jobs:
         id: get-composer-cache-dir
         run: |
           echo "::set-output name=dir::$(composer config cache-files-dir)"
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: composer-cache
         with:
           path: ${{ steps.get-composer-cache-dir.outputs.dir }}