Snow Under Trees (Fabric)

• Added support for 1.21.5
• Added German translations, thank you @Lucanoria.

• Updated Russian translations, thanks @achookh for this.
• Added support for Snowbound's Boreal Forest.
• Updated YACL.

• Dropped support for 1.20.1, 1.20.4, 1.20.6
• Added support for 1.21.2/3 and 1.21.4

I do apologize for how long this fix took, it was difficult to pin-point the exact reason these freezes and crashes were occuring. Thank you for your patience.

• Fix issues with serene seasons compatibility causing random freezes and crashes in singleplayer and on dedicated servers.

• Fix logspam when serene seasons is installed.
• Fix deadlock issues (hopefully.)