Remove caching layer in PHPUnit workflow

There are not enough packages and updates that justify keeping an action up to date

.github/workflows/phpunit.yml

@@ -61,19 +61,6 @@ jobs:
           MYSQL_PORT: ${{ job.services.mysql.ports[3306] }}
         run: bash bin/install-wp-tests.sh wordpress_test root password "127.0.0.1:$MYSQL_PORT" "$WP_VERSION"
 
-      - name: Get Composer cache directory
-        id: composer-cache
-        run: |
-          echo "::set-output name=dir::$(composer config cache-files-dir)"
-
-      - name: Setup cache
-        uses: pat-s/[email protected]
-        with:
-          path: ${{ steps.composer-cache.outputs.dir }}
-          key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.lock') }}
-          restore-keys: |
-            ${{ runner.os }}-composer-
-
       # wearerequired/coding-standards is not compatible with PHP 8 and is not needed for PHPUnit
       - name: Remove coding standards
         run: composer remove --dev wearerequired/coding-standards --ignore-platform-reqs