Use `flask` in lieu of `black` for tool tests

[charliermarsh]

Summary

On my machine, this reduces the test time from ~12 seconds to 4-5 seconds, since the package is so much smaller and the cold starts aren't as dramatic as black.

[zanieb]

Let's just create a project in astral-test? It should be trivial to publish a package with some entry points. I can do it this week.

[charliermarsh]

Ok, but I need this like... ASAP. The tests are so slow for me. I suppose I can do it now.

[zanieb]

I don't mind if you merge this in the meantime but it feels like a bit of a hack and I don't love the extra being included. 🤷‍♀️

[charliermarsh]

Can I change it to Flask in the meantime?