Fix latest php-cs-fixer requirements

Author: mlocati

.github/workflows/tests.yml

@@ -16,7 +16,7 @@ jobs:
       - name: Setup PHP
         uses: shivammathur/setup-php@v2
         with:
-          php-version: "7.2"
+          php-version: "8.1"
           extensions: mbstring, zip
           tools: composer:2, php-cs-fixer:3
           coverage: none