Bug fixes:

- Fixed an oversight where Loader can try to open a GUI in a headless environment

Changes:

- Mixin compatibility level for quilt mods is currently set to 0.10.0. We'll add a way to change this in the future.

Changes from updating Fabric Loader from 0.15.11 to 0.16.2:

- Updated mixin extras to 0.4.1
- Updated mixin to 0.15.2+mixin.0.8.7
- Added version parsing support for 1.21.2
- Include full entrypoint definition in entrypoint crashes.
