Drop Python 3.9 support

[ezio-melotti]

This PR drops Python 3.9 support.

There are two reasons for this:

• Python 3.9 recently reached EOL;
• coverage now requires Python 3.10 (see Bump the pip group with 3 updates #433)

Previous PR here:

• Drop support for EOL Python 3.8 #407

Before merging we also need an admin (@Mariatta?) to remove the 3.9 checks from the branch settings.

[ezio-melotti]

@Mariatta, can you remove 3.9 from the checks in the repo settings?

[AA-Turner]

can you remove 3.9 from the checks in the repo settings?

cc @python/organization-owners (3.13 & 3.14 aren't required, but 3.9-3.12 are)

A

[hugovk]

I suggest we remove these required status checks?

We're pretty good at only merging when things are green 😇 and I don't think this repo needs as strict rules as https://github.com/python/cpython.

[AA-Turner]

I suggest we remove these required status checks?

Seconded

[ambv]

Done and done!

[AA-Turner]

Thanks @ambv!

A

[ezio-melotti]

Thanks @ambv!

While you are at it, would you mind setting merged branches to be auto-deleted?

"Automatically delete head branches" at the end of https://github.com/python/blurb_it/settings#merge-button-settings

[ambv]