ci: fix hashFiles expression quotes (single quotes required)

Author: Vitexus

.github/workflows/php.yml

@@ -15,12 +15,12 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v4
 
     - name: Setup PHP 8.4
       uses: shivammathur/setup-php@v2
       with:
-        php-version: "8.4"
+        php-version: '8.4'
 
     - name: Validate composer.json and composer.lock
       run: composer validate --strict
@@ -30,7 +30,7 @@ jobs:
       uses: actions/cache@v5
       with:
         path: vendor
-        key: ${{ runner.os }}-php-${{ hashFiles("**/composer.lock") }}
+        key: ${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}
         restore-keys: |
           ${{ runner.os }}-php-