progress on 1.21 transition

src/main/resources/item_groups.yml

@@ -121,7 +121,6 @@ wearable:
     - player_head
     - creeper_head
     - dragon_head
-    # do not exist in 1.18 but exist in future update
     - piglin_head
   groups:
     - armors

src/main/resources/plugin.yml

@@ -4,7 +4,7 @@ prefix: "Custom Anvil"
 version: ${version}
 folia-supported: true
 description: Allow to customise anvil mechanics
-api-version: 1.16
+api-version: 1.21
 load: POSTWORLD
 authors: [ DelilahEve, alexcrea ]
 libraries: [${libraries}]