Add error code to bare type ignore

[jonyscathe]

Hey, after PR #489 my generated code is failing mypy with option ignore-without-code due to bare type ignore comments.

The error I am getting is:
myfile.pyi:16: error: "type: ignore" comment without error code (consider "type: ignore[misc, type-arg]" instead) [ignore-without-code]

Any objections to [misc, type-arg] being thrown on the end of the type ignore comments generated here: https://github.com/nipunn1313/mypy-protobuf/blob/main/mypy_protobuf/main.py#L727 ?

Or I can always turn that mypy option off for this particular project.