boto: drop dependency on types-six

[hauntsaninja]

For typeshed-internal/stub_uploader#61 (comment)

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[AlexWaygood]

Just to state explicitly what's going on here:

1. boto at runtime does, in fact, still use six internally
2. But typeshed only supports Python 3, and six.http_client is the same as http.client on Python 3
3. So that we can allow non-types dependencies without introducing a security hole, it's useful to ban stubs from having any dependencies if the runtime package they're stubs for doesn't also have that dependency. This applies to stub dependencies as well, since they're also now potentially dangerous given that stubs can now have non-stubs dependencies.
4. boto doesn't actually, officially, depend on six at runtime, it just vendors six. This means that the machinery in the stub-uploader can't detect that boto uses six at runtime, ergo types-boto also cannot depend on types-six. And because of point (2) above, it's not a big deal to remove the dependency.

[AlexWaygood]

Suggested change

requires = []