Update README.md

Author: Edivad99

README.md

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 # ExtraStorage
-![ExtraStorage CI](https://github.com/Edivad99/ExtraStorage/workflows/ExtraStorage%20CI/badge.svg?branch=1.20.x)
+![ExtraStorage CI](https://github.com/Edivad99/ExtraStorage/workflows/ExtraStorage%20CI/badge.svg?branch=1.21.x)
 [![CurseForge](http://cf.way2muchnoise.eu/full_410168_downloads.svg)](https://www.curseforge.com/minecraft/mc-mods/extrastorage)
 [![Modrinth Downloads](https://img.shields.io/modrinth/dt/T34cBZKl?label=Modrinth%20Downloads)](https://modrinth.com/mod/extrastorage)