Add PHP 8.3 and 8.4 to matrix

Author: ruudk

.github/workflows/test.yaml

@@ -13,6 +13,8 @@ jobs:
           - '8.0'
           - '8.1'
           - '8.2'
+          - '8.3'
+          - '8.4'
     steps:
       - name: Checkout
         uses: actions/checkout@v2