ci: Add tests for PHP 8.4 (#21)

Author: theofidry

.github/workflows/tests.yaml

@@ -24,6 +24,7 @@ jobs:
                     - "8.1"
                     - "8.2"
                     - "8.3"
+                    - "8.4"
                 symfony:
                     - "unchanged"
                     - "6.*.*"
@@ -64,7 +65,7 @@ jobs:
             fail-fast: true
             matrix:
                 php:
-                    - "8.3"
+                    - "8.4"
 
         steps:
             -   name: "Check out repository code"