use max_length argument as varchar length

Author: itsbekas

sqlmodel/_compat.py

@@ -201,7 +201,9 @@ def get_field_metadata(field: Any) -> Any:
         for meta in field.metadata:
             if isinstance(meta, PydanticMetadata):
                 return meta
-        return FakeMetadata()
+            fake = FakeMetadata()
+            fake.max_length = getattr(meta, "max_length", None)
+            return fake
 
     def post_init_field_info(field_info: FieldInfo) -> None:
         return None