Update main target versions

Signed-off-by: Joas Schilling <coding@schilljs.com>

.github/workflows/phpunit.yml

@@ -14,7 +14,7 @@ jobs:
       matrix:
         php-versions: ['7.4']
         databases: ['sqlite']
-        server-versions: ['stable21', 'stable22', 'master']
+        server-versions: ['stable21', 'stable22', 'stable23', 'stable24', 'master']
 
     name: php${{ matrix.php-versions }}-${{ matrix.databases }}-${{ matrix.server-versions }}