Add create_language endpoint

src/app/serializers.py

@@ -1,12 +1,15 @@
 from pydantic import BaseModel, constr
 
 
-class LanguageDetail(BaseModel):
-    id: int
+class CreateLanguage(BaseModel):
     label: constr(max_length=16)  # type: ignore
     code: constr(max_length=4)  # type: ignore
 
 
+class LanguageDetail(CreateLanguage):
+    id: int
+
+
 class UserBase(BaseModel):
     user_id: int
     last_name: constr(max_length=64)  # type: ignore