[TASK] Also PHP-lint with PHP 8.3 on CI (#477)

This is the backport of #426 to the maintenance branch.

Author: oliverklee

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        php-version: [ '5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0', '8.1', '8.2' ]
+        php-version: [ '5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0', '8.1', '8.2', '8.3' ]
 
     steps:
       - name: Checkout