Pin CI version of click to resolve mypy error

[zanieb]

CI is failing (e.g. #2768) because of a mypy/click bug ref pallets/click#2558

❯ mypy httpx
httpx/_main.py:308: error: Argument 1 has incompatible type "Callable[[str, str, list[tuple[str, str]], str, list[tuple[str, str]], list[tuple[str, File]], str, list[tuple[str, str]], list[tuple[str, str]], tuple[str, str] | None, str, float, bool, bool, bool, BinaryIO | None, bool], None]"; expected <nothing>  [arg-type]
Found 1 error in 1 file (checked 24 source files)

This is resolves the type error by temporarily adding a bound to the supported click version and can be reverted once the bug is fixed upstream.

Additional refs pallets/click#2559 pallets/click#2562 python/mypy#13449

[Kludex]

It looks like a release in click will happen soon, fyi

[zanieb]

I tried the linked pull request locally and it didn't work — figure we might as well be unblocked in the meantime but don't have strong feelings.

[tomchristie]

Ah well caught.

We'd probably want to resolve a CI failure by pinning in requirements.txt, rather than in our packaging.

figure we might as well be unblocked in the meantime

Yep.

[zanieb]

@tomchristie done!