Expose metadata to sphinx

[pkulev]

Hello! First of all thank you for the wonderful package!
I enjoy using it for writing my documentation ❤️.

I use sphinx v5.3.0 with parallel builds (-j auto) and it shows the following warning:

WARNING: the sphinx_code_tabs extension does not declare if it is safe for parallel reading, assuming it isn't - please ask the extension author to check and make it explicit
WARNING: doing serial read

I tinkered through the code and thought that it's pretty safe for parallel reads.
I looked into the docs and then made changes for passing metadata info to the sphinx application.

This PR also contains some style fixes according to common practices (pep8, black, isort), but if you don't want them - I will drop those style-related commits.

[coldfix]

Thanks!

This PR also contains some style fixes according to common practices (pep8, black, isort), but if you don't want them - I will drop those style-related commits.

Could you drop that please for this PR. That should go in a separate PR, where it can be discussed independently. There are also some changes for which I don't see a clear reason immediately (e.g. changing lists to sets).

You don't need to increase the version number either. I will do that in the release commit :)

[coldfix]

Also, while I think the idea of on autoformatter is good in general, I'm not a big fan of black specifically, as it often leads to very suboptimal formatting (IMO). I've seen many instances of code which is just not very readable anymore after what black does to it.

[pkulev]

I understand your point.
I've already used to autoformatting and it makes great sense for me on large code bases when I have to only review logic and pass formatting and style-related things to the machine 😄

I've dropped those commits.

[coldfix]

Thanks, so much easier to see the relevant change now!