Update PHP version matrix in CI workflow to only include PHP 8.4

Author: chriskacerguis

.github/workflows/ci.yml

@@ -52,7 +52,7 @@ jobs:
       fail-fast: false
       matrix:
         # php: ['8.1', '8.2', '8.3', '8.4']
-        php: ['8.1', '8.2', '8.3', '8.4']
+        php: ['8.4']
     steps:
       - name: Checkout
         uses: actions/checkout@v4