Add m2w64 compilers for windows

[twiecki]

It seems like currently we are not installing the right compilers for windows.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[twiecki]

@conda-forge-admin please rerender

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I wanted to let you know that I linted all conda-recipes in your PR (recipe) and found some lint.

Here's what I've got...

For recipe:

• Selectors are suggested to take a <two spaces>#<one space>[<expression>] form. See lines [39, 40]

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[twiecki]

@conda-forge-admin, please rerender

[twiecki]

@conda-forge-admin, please rerender

[github-actions]

Hi! This is the friendly automated conda-forge-webservice.
I tried to rerender for you, but it looks like there was nothing to do.

[twiecki]

@conda-forge-admin, please rerender

[brandonwillard]

Thanks for looking into this! I don't know what the situation is with these Windows dependencies, so I can't really say what's correct or not; however, it seems like the PyPy builds are failing, and that makes sense given our non-trivial dependencies and direct use of CPython-based extensions.

In other words, I don't know if we should be running PyPy tests in the first place.