chore: remove unused actions/cache

Author: tinect

.github/workflows/php.yml

@@ -39,15 +39,6 @@ jobs:
     - name: Validate composer.json and composer.lock
       run: composer validate --strict
 
-    - name: Cache Composer packages
-      id: composer-cache
-      uses: actions/cache@v2
-      with:
-        path: vendor
-        key: ${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}
-        restore-keys: |
-          ${{ runner.os }}-php-
-
     - name: Install dependencies
       run: composer install --prefer-dist --no-progress --no-interaction