Test against PHP 8.4 (povils#183)

Author: sidz

.github/workflows/ci.yaml

@@ -18,7 +18,7 @@ jobs:
     strategy:
       matrix:
         operating-system: [ ubuntu-latest ]
-        php-version: ['7.4', '8.0', '8.1', '8.2', '8.3']
+        php-version: ['7.4', '8.0', '8.1', '8.2', '8.3', '8.4']
         symfony-require: ['^4', '^5', '^6', '^7']
         composer-flags: [ '' ]
         exclude: