fix: Remove Meta from Model (#215)

Pyright 1.1.339 enabled reportIncompatibleVariableOverride=true as part of new default "standard" mode.

https://github.com/microsoft/pyright/releases/tag/1.1.339

This leads to

> error: "Meta" overrides symbol of same name in class "Model"

At runtime, models do not have `Meta` if it's not defined, so it's safe to remove it.

django-stubs/db/models/base.pyi

@@ -26,7 +26,6 @@ class Model(metaclass=ModelBase):
     _default_manager: ClassVar[BaseManager[Self]]
     objects: ClassVar[BaseManager[Self]]
 
-    class Meta: ...
     pk: Any = ...
     _state: ModelState
     def __init__(self, *args: Any, **kwargs: Any) -> None: ...