Update to 1.21 and fix a vital crash.

Update support for 1.20.5&6

IT HAS UPDATED!!!

add support for 1.20.3/1.20.4. If you have downloaded an older version and it doesn't work, please try this new one. If still not work, please let me know via e-mail or GitHub Issues.

WARNING

Fabric loader v0.15.0 or higher(which also acquires fabric API v0.91.1 or higher) is required in this version.

stable test for 1.20.3

support for 1.16-1.16.3