Improve pyright compatibility

[FasterSpeeding]

Summary

The main aim for this PR is (as the title says) to improve compatibility with pyright. While this PR doesn't go as far as to introduce pyright as an internally used static analyser (since there's just too many internal incompatibilities right now), it does introduce pyright's "verifytypes" check as a pipeline and nox task; verifytypes is a cli command used to verify the "type completeness" of a library's exported types (https://github.com/microsoft/pyright/blob/main/docs/typed-libraries.md probably gives some insight into that concept).

The main implication of pyright's type completeness is that public exported variables and attributes must be explicitly typed (likely to allow for static analysis with the lib without having to go deeper into the lib itself to infer types than just the actual interface) and, while this PR does introduce a couple of other pyright compatibility fixes, the majority of the pyright compatibility fixes are to appease this.

It's worth noting that this PR had to change the _about variables to be explicitly typed and the sed scripts used for bumping the version so @davfsa will want to check over that code to make sure I didn't break anything.

Checklist

• I have run nox and all the pipelines have passed.
• I have made unittests according to the code I have added/modified/deleted.

Related issues

[davfsa]

Will check if sed will still work, but my idea is that it should

EDIT: It does :)

.