DEPS: Drop Python 3.9

[mroeschke]

Dropping Python 3.9 support per NEP 29 and SPEC-0

[tqa236]

Should Python :: 3.8 be removed as well?

[mroeschke]

Good catch. Yes definitely

[mroeschke]

(This is a testing file so not critical but still useful)

[twoertwein]

I think there are a few sys.version_info left that compare aginst 3.10, for example, in pandas._typing. Pyupgrades's --py310-plus might take care of that automatically (currently set to 3.9)

[Dr-Irv]

I only looked at _typing.py

[WillAyd]

lgtm. Do we want to wait until we get closer to 3.0 release to merge?

[mroeschke]

Do we want to wait until we get closer to 3.0 release to merge?

I guess we could merge anytime, but I would wait a little just in case people are still using 3.9 nightlies

[lithomas1]

Are people OK with doing this now?

We're coming up on the Python 3.10 drop date (end of this year) as well.

I would personally prefer dropping as close to the date specified by SPEC 0, so people aren't surprised when this happens.

[mroeschke]

Since it seemed like there was approval a few months ago, I'll merge at the end of the week if there are no objections

[WillAyd]

Works for me