Minimum Python version for 21.1 is 3.6.2

[philthompson10]

Because of the use of typing.NoReturn I think the minimum Python version for 21.1 should be 3.6.2 rather than just 3.6.

Phil

[pfmoore]

If typing added a name in 3.6.2, that sounds like a breaking change that probably shouldn't have been allowed by CPython 🙁

This appears to have been introduced in #9424. We used NoReturn before that, but it was guarded by if TYPE_CHECKING, so didn't affect runtime behaviour.

[jamescurtin]

👋 I put up a PR to resolve this. As I am a first-time contributor, could a maintainer please unblock the CI?

Thank you!

[pfmoore]

that sounds like a breaking change that probably shouldn't have been allowed by CPython

Actually the typing library is provisional in 3.6, so this is allowable. We probably shouldn't have been quite so quick to remove the if TYPE_CHECKING guards...