Add PHP 8.1 to CI

Author: derrabus

Diff for: .github/workflows/ci.yml

@@ -20,6 +20,9 @@ jobs:
                     - php: '8.0'
                       deps: highest
                       deprecations: max[indirect]=5
+                    - php: '8.1'
+                      env:
+                          SYMFONY_PHPUNIT_VERSION: '9.5'
 
         steps:
             - name: Checkout code