use PHP8.4 for testing

Author: tdebatty

.github/workflows/php.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
 
     container:
-      image: cylab/php:8.3
+      image: cylab/php:8.4
 
     steps:
     - uses: actions/checkout@v4