Mypy in 3.10 does not respect the python version when checking .pyi files

[rchui]

Mypy installed in a python 3.10 docker container fails to parse a .pyi file with the following error:

usr/local/lib/python3.10/site-packages/numpy/__init__.pyi:636: error: Positional-only parameters are only supported in Python 3.8 and greater
Found 1 error in 1 file (errors prevented further checking)

To Reproduce

1. docker run -it --rm python:3.10 bash
2. pip install numpy mypy
3. Create a test.py with:

import numpy

4. Run mypy test.py

Expected Behavior

I expect mypy to be able to parse this .pyi file successfully given that it is being run from a python 3.10 interpreter. The error fails because it attempts to parse it with an incompatible version that does not have positional-only parameters.

I am also unable to squash this error because it seems to happen at a stage where errors can't be silenced.

Actual Behavior

The above error occurs. I have tested that this error does not occur in python 3.9. It occurs across multiple operating systems including MacOS and Linux, across both amd64 and arm64 architectures, across multiple versions of mypy, and multiple versions of numpy

Your Environment

• Mypy version used: 0.971
• Mypy command-line flags: None
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.10
• Operating system and version: MacOS

[AlexWaygood]

Duplicate of #13499

[AlexWaygood]

See my comments here: #13627 (comment)

[hauntsaninja]

(In particular, the easiest fix is to stick with Python 3.10.6 for now)