ci: add PHP 8.4 to test matrix

Author: stklcode

.github/workflows/test.yml

@@ -5,7 +5,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php: [ '5.6', '7.4', '8.0', '8.1', '8.2', '8.3' ]
+        php: [ '5.6', '7.4', '8.0', '8.2', '8.4' ]
     steps:
       - name: Checkout
         uses: actions/checkout@v4