ci: test PHP 8.3 support

Author: xel1045

.github/workflows/tests.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        php: [8.1, 8.2]
+        php: [8.1, 8.2, 8.3]
         laravel: [10.*, 11.*]
         dependency-version: [prefer-lowest, prefer-stable]
         exclude: