Test code for PHP8.3 compatibility

The earlier versions are more relevant as we already test with 8.3 but
doing the explicit check shouldn't hurt.

Author: vmcj

.github/workflows/codestyle.yml

@@ -49,7 +49,7 @@ jobs:
       image: pipelinecomponents/php-codesniffer:latest
     strategy:
       matrix:
-        PHPVERSION: ["8.1", "8.2"]
+        PHPVERSION: ["8.1", "8.2", "8.3"]
     steps:
       - run: apk add git
       - uses: actions/checkout@v4