include PHP 8.3 and 8.4 in test matrix

Author: Sephster

.github/workflows/tests.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: [8.1, 8.2]
+        php: [8.1, 8.2, 8.3, 8.4]
         os: [ubuntu-22.04]
         stability: [prefer-lowest, prefer-stable]
         include: