add PHP 8.3 with latest WP to build matrix

Author: stklcode

.github/workflows/tests.yml

@@ -39,7 +39,7 @@ jobs:
         options: --health-cmd="mysqladmin ping" --health-interval=10s --health-timeout=5s --health-retries=3
     strategy:
       matrix:
-        php: ['8.2']
+        php: ['8.3']
         wordpress: ['nightly', 'latest']
         include:
           - php: '8.2'