fix field description to be _StrOrPromise (#35)

compat with mypy 1.16

Co-authored-by: sobolevn <[email protected]>

Author: asottile-sentry

django-stubs/db/models/fields/__init__.pyi

@@ -130,7 +130,7 @@ class Field(RegisterLookupMixin, Generic[_ST, _GT]):
     model: type[Model]
     name: str
     verbose_name: _StrOrPromise
-    description: str | _Getter[str]
+    description: _StrOrPromise | _Getter[_StrOrPromise]
     blank: bool
     null: bool
     unique: bool