bump PHP version

Author: TheDigitalOrchard

.github/workflows/php.yml

@@ -20,7 +20,7 @@ jobs:
     - name: Setup PHP with specific version
       uses: shivammathur/setup-php@v2
       with:
-        php-version: '5.4'
+        php-version: '5.6'
 
     - name: Validate composer.json and composer.lock
       run: composer validate --strict