Bump setuptools in pyproject.toml to >=51.0.0?

[FollowTheProcess]

Describe the bug

While doing some digging in the setuptools documentation I came across this section: https://setuptools.pypa.io/en/latest/userguide/declarative_config.html#options which (if I'm reading it correctly) suggests that in order to use the options.entry_points key (as we do in our setup.cfg here), you must use setuptools >= 51.0.0.

Currently we specify setuptools >= 42 in pyproject.toml here

If this is correct and I'm not reading it wrong, does this mean we could get a broken install if someone uses setuptools < 51?

Given that no one (to my knowledge) has raised an issue about this I think it's safe to assume no one has fell foul of this, but it seems like something we should fix?

[DiddiLeija]

I agree. I don't know if we'll break something in the process, though.

[henryiii]

What the... Pretty sure this is not new in 51. It's been around as long as I can remember.

[henryiii]

Thinking they meant to put "41" not "51", perhaps.

[layday]

Pretty sure that existed even before 41. In fact it appears to have been there in the very first version of setup.cfg: pypa/setuptools#862.

[cjolowicz]

Closing as per #553 (comment), thanks @layday and @henryiii