Update to Minecraft 1.21.8, add checkstyle, fix compilation errors

- Update Paper API: 1.20.1 -> 1.21.4
- Update plugin version: 1.5.5-1.20.1 -> 1.5.5-1.21.8
- Add checkstyle plugin with reasonable rules
- Fix Enchantment.LUCK -> Enchantment.UNBREAKING
- Fix EntityType.FIREWORK -> EntityType.FIREWORK_ROCKET
- Remove unused imports
- Add temp_*/ to .gitignore
- 118 files changed, 1633 insertions(+), 1301 deletions(-)

lohub/src/main/resources/plugin.yml

@@ -15,13 +15,13 @@ commands:
     description: Teleport to spawn
     usage: /hub
     permission: lohub.hub
-    aliases: [spawn, хаб, спавн]
+    aliases: [ spawn, хаб, спавн ]
   
   sethub:
     description: Set hub spawn location
     usage: /sethub
     permission: lohub.admin
-    aliases: [setspawn, установитьспавн]
+    aliases: [ setspawn, установитьспавн ]
   
   lohub:
     description: LoHub admin command