Issue Description: The latest dynmap release does not appear to support Paper 1.16.3

• Dynmap Version: 3.1-beta-3a
• Server Version: paper 1.16.3 build 198
• Pastebin of crashlogs or other relevant logs: https://pastebin.com/2skYzyER

[X] I have looked at all other issues and this is not a duplicate
[X] I have been able to replicate this

This isn't a bug, the latest release doesn't support 1.16.3 but the latest dev build does.

You can find a link in the announcements channel of the discord or on reddit