Remember to unpin pytest

[takluyver]

In #2364, I pinned pytest<8 to avoid a bug in pytest 8.0rc1 which was causing some of our tests to fail. It looks like people are working on fixing that. We should remember to unpin pytest again at some point.

[woutdenolf]

A fix has been merged: pytest-dev/pytest#11825

[lesteve]

pytest 8.0.0rc2 has been released with the fix, I opened #2371 to unpin pytest. Hopefully CI is green, we'll see 😉

[takluyver]

Thanks both 😃