Support Pythons <4

[cpcloud]

I'd like to be able to allow python <4 in ibis, but as of this PR (ibis-project/ibis#4797) I cannot due to this library's <3.11 pin.

[chalmerlowe]

@cpcloud
Been speaking with @tswast about removing the pinned upper bound.
I don't see any problem with doing so. Let me take a look at the PR and see what we can arrange.