Immersive Storms for MC 1.21.9

Immersive Storms has now been updated to Minecraft 1.21.9. This update also comes with an overhaul to the Config system, replacing Cloth Config with YACL. Existing configs will be automatically migrated to the new system, if they are found. No config options have been added or removed.

• Updated to Minecraft 1.21.9
• Migrated from Cloth Config to YACL