Fix phpstan workflow

Author: jaapio

.github/workflows/push.yml

@@ -153,14 +153,13 @@ jobs:
     needs: [setup, phpunit]
     steps:
       - uses: actions/checkout@master
-      - name: Restore/cache vendor folder
-        uses: actions/cache@v1
+      - name: composer
+        uses: docker://composer
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
-          path: vendor
-          key: all-build-${{ hashFiles('**/composer.lock') }}
-          restore-keys: |
-            all-build-${{ hashFiles('**/composer.lock') }}
-            all-build-
+          args: install --no-interaction --prefer-dist --optimize-autoloader
+
       - name: PHPStan
         uses: phpDocumentor/[email protected]
         env: