feat: add delete avatar

src/infrastructure/database/repositories/user_repository.py

@@ -89,7 +89,7 @@ class UserRepository(IUserRepository):
     async def set_encrypted_mnemonic(self, user_id: str, encrypted_mnemonic: str) -> UserEntity:
         return await self._update_field(user_id, encrypted_mnemonic=encrypted_mnemonic)
 
-    async def set_avatar_link(self, user_id: str, avatar_link: str) -> UserEntity:
+    async def set_avatar_link(self, user_id: str, avatar_link: str | None) -> UserEntity:
         return await self._update_field(user_id, avatar_link=avatar_link)
 
     async def get_password_hash(self, user_id: str) -> str: