Fix error on purge with sql-storage

Author: TBlueF

BlueMapCore/src/main/java/de/bluecolored/bluemap/core/storage/sql/SQLStorage.java

@@ -398,8 +398,8 @@ public void purgeMap(String mapId, Function<ProgressInfo, Boolean> onProgress) t
                 );
 
                 executeUpdate(connection,
-                        "DELETE t " +
-                        "FROM `bluemap_map`" +
+                        "DELETE " +
+                        "FROM `bluemap_map` " +
                         "WHERE `map_id` = ?",
                         mapId
                 );