Add PHP8.4 to matrix of test envs

Author: jerowork

.github/workflows/test.yaml

@@ -11,7 +11,7 @@ jobs:
     name: Test
     strategy:
       matrix:
-        php-version: ['8.3']
+        php-version: ['8.3', '8.4']
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code