Issue Description: Sign Markers do not work on Fabric when placed as Non-Op or as Op. Signs placed are not processed and do not show on map

• Dynmap Version: 3.1-beta5-fabric-1.16.2
• Server Version: fabric-loader-0.10.6-1.16.2 / [email protected]+1.16
• Pastebin of Configuration.txt: https://pastebin.com/3k47n08J
• Server Host (if applicable): Selfhosted
• Pastebin of crashlogs or other relevant logs: n/a
• Other Relevant Data/Screenshots: n/a
• Steps to Replicate:

1. Fresh install of server and only mods required (fabric api and dynmap)
2. Set config to enable sign markers
3. Join server with Op user and place a sign with required tag and text

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

Added in b31d7eb#diff-0d6acfca1f719076eaf25937ea1c1a9ea2cf1f8943ee78a856133e7dcdd42e38

Note, for now it only works on 1.18+. Backport is planned but no ETA atm.