Support for 1.20 and several bug fixes.

Please consider supporting me on my Ko-fi page (although my sponsor page should be going live soon). Although I do this for free, it takes a considerable amount of time and effort:
https://ko-fi.com/theguyhere

COMPATIBILITY NOTICE
All you need to do is replace the old jar with the current one. No other changes are necessary.

Feature Changes
Additions

• Added support for 1.20 and 1.20.1

Changes

• Changed all upgraded tipped arrows to extended rather than upgraded

Bug Fixes

• Fixed a bug where attempting to give the player a null item would leave an error in the console
• Fixed a bug where attempting to modify attributes that don't already exist in a mob results in errors in the console
• Fixed a bug where a nonexistent tipped arrow was attempted to be called