Bump biome_lib from `396ca88` to `3d21795`

Bumps [biome_lib](https://github.com/mt-mods/biome_lib) from `396ca88` to `3d21795`.
- [Release notes](https://github.com/mt-mods/biome_lib/releases)
- [Commits](https://github.com/mt-mods/biome_lib/compare/396ca881dfea09fae6671dcd17486b356485cd8a...3d217950b33c922da3a13ca76254976eb7530daf)

biome_lib @ 3d217950

-Subproject commit 396ca881dfea09fae6671dcd17486b356485cd8a
+Subproject commit 3d217950b33c922da3a13ca76254976eb7530daf