test php8 compatibility

Author: Insolita

.github/workflows/test.yml

@@ -32,6 +32,7 @@ jobs:
       with:
         php-version: ${{ matrix.php-versions }}
         extensions: mbstring, intl, gd, imagick, zip, dom, pgsql
+        tools: php-cs-fixer, phpunit:${{ matrix.phpunit-versions }}
       env:
           update: ${{ matrix.php-version == '8.0' || matrix.php-version == '8.1' }}
     - name: Get composer cache directory