Testsuite fails if mypy isn't installed

[eli-schwartz]

... And therefore it's not clear what the expectations here are. I'm packaging wrapt as a Linux distro package: https://bugs.gentoo.org/964960

Am I "obligated" to run mypy tests in order to ensure that wrapt is in good working order on Gentoo / various pythons supported by Gentoo / various niche CPU architectures supported by Gentoo (in the sense that we do intentionally want to runtestsuites for all packages, and now wrapt is running these mypy tests)?

If so, I may need to look into making mypy available in a bunch more places, e.g. mips/alpha/hppa. If not, then having those tests be automatically skipped when the mypy cli program isn't installed and 'CI' not in os.environ, would be beneficial to us.

[GrahamDumpleton]

You can test against develop branch to see if changes satisfy your requirement.