Refactor import for SkinPartBuilder to correct package

Moved the import for SkinPartBuilder to the appropriate package under `net.thenextlvl.character.skin`. This ensures proper organization and resolves potential conflicts or ambiguities in references.

src/main/java/net/thenextlvl/character/plugin/CharacterPlugin.java

@@ -17,7 +17,6 @@
 import net.thenextlvl.character.Character;
 import net.thenextlvl.character.CharacterController;
 import net.thenextlvl.character.PlayerCharacter;
-import net.thenextlvl.character.SkinPartBuilder;
 import net.thenextlvl.character.plugin.command.CharacterCommand;
 import net.thenextlvl.character.plugin.controller.PaperCharacterController;
 import net.thenextlvl.character.plugin.listener.ConnectionListener;
@@ -29,6 +28,7 @@
 import net.thenextlvl.character.plugin.serialization.LocationAdapter;
 import net.thenextlvl.character.plugin.serialization.ProfilePropertyAdapter;
 import net.thenextlvl.character.plugin.serialization.WorldAdapter;
+import net.thenextlvl.character.skin.SkinPartBuilder;
 import org.bstats.bukkit.Metrics;
 import org.bukkit.Location;
 import org.bukkit.World;