ci: Fix lint errors due to mypy with python 3.12

[favilo]

Now that we're using python 3.12 for the lint github action, we need to fix the errors that it is reporting.

Lint errors in question

• Have you signed the contributor license agreement?
• Have you followed the contributor guidelines?
• Have you run make check-all successfully?
• Did you choose a descriptive title and description for your PR?
• (Only for maintainers) Did you apply appropriate labels and a milestone?

[gbanasiak]

This is caused by aiohttp update, which is a transitive/unpinned dependency in Rally.

After local venv recreation:

-aiohttp==3.10.8
+aiohttp==3.11.0

It's either/or it seems. Either we pin aiohttp and previous version is OK, or we let aiohttp move and then need to remove mypy ignore. WDYT @favilo ?

[favilo]

How about we pin to the current version. Then we can remove the ignore and have an updated dependency, without being forced to upgrade from an unpinned one.

[favilo]

I've also moved the license comment to here.

[favilo]

Ah, so currently Python 3.8 isn't supported. So I'll pin it to 3.10.8. But I'm going to take this opportunity to just remove python 3.8 support in the near future. I've already got it working with 3.12 just fine.

That will allow us to do a lot more of the improvements we were interested in doing, too.