Merge pull request #138 from Yoast/JRF/ghactions-run-against-php83

GH Actions: enable linting and testing against PHP 8.3

Author: jrfnl

.github/workflows/test.yml

@@ -41,7 +41,7 @@ jobs:
 
     strategy:
       matrix:
-        php_version: ['5.4', '5.5', '5.6', '7.0', '7.2', '7.3', '7.4', '8.0', '8.1']
+        php_version: ['5.4', '5.5', '5.6', '7.0', '7.2', '7.3', '7.4', '8.0', '8.1', '8.3']
         coverage: [false]
 
         # Run code coverage only on high/medium/low PHP.