Fix maintained icon

Signed-off-by: minggangli <[email protected]>

README.md

@@ -4,7 +4,7 @@ madedit-mod
 [![Build Status](https://img.shields.io/travis/LiMinggang/madedit-mod/master.svg?label=Linux)](https://travis-ci.org/LiMinggang/madedit-mod)
 [![GitHub Latest release](https://img.shields.io/github/release/LiMinggang/madedit-mod/all.svg)](https://github.com/LiMinggang/madedit-mod/releases)
 [![GitHub issues](https://img.shields.io/github/issues/LiMinggang/madedit-mod.svg)](https://github.com/LiMinggang/madedit-mod/issues)
-[![Maintained](https://img.shields.io/maintenance/yes/2021.svg)](https://github.com/LiMinggang/madedit-mod/commits/master)
+[![Maintained](https://img.shields.io/maintenance/yes/2023.svg)](https://github.com/LiMinggang/madedit-mod/commits/master)
 [![Ohloh Project Status](https://www.openhub.net/p/madedit-mod/widgets/project_thin_badge.gif)](https://www.openhub.net/p/madedit-mod)
 [![Download MadEdit-Mod](https://img.shields.io/sourceforge/dt/madedit-mod.svg)](https://sourceforge.net/projects/madedit-mod/files/)