Warn on MariaDB servers (#20862)

```release-note
NONE
```

store/sqlstore/store.go

@@ -1104,7 +1104,7 @@ func (ss *SqlStore) ensureMinimumDBVersion(ver string) (bool, error) {
 	case model.DatabaseDriverMysql:
 		// Usually a version string is of the form 5.6.49-log, 10.4.5-MariaDB etc.
 		if strings.Contains(strings.ToLower(ver), "maria") {
-			mlog.Debug("MariaDB detected. Skipping version check.")
+			mlog.Warn("MariaDB detected. You are using an unsupported database. Please consider using MySQL or Postgres.")
 			return true, nil
 		}
 		parts := strings.Split(ver, "-")