fix(ci): Align mariadb versions with list of supported versions

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

.github/workflows/phpunit-mariadb.yml

@@ -53,7 +53,7 @@ jobs:
     strategy:
       matrix:
         php-versions: ['8.1']
-        mariadb-versions: ['10.3', '10.4', '10.5', '10.6', '10.11']
+        mariadb-versions: ['10.3', '10.5', '10.6', '10.11']
         include:
           - php-versions: '8.3'
             mariadb-versions: '10.6'