add PHP 8.4 to the testing matrix in GitHub Actions

Author: nadar

.github/workflows/tests.yml

@@ -37,7 +37,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest]
-        php: ['5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0', '8.1', '8.2', '8.3']
+        php: ['5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0', '8.1', '8.2', '8.3', '8.4']
     steps:
       ## checkout the repoistory
       - name: Checkout Repo