feat: add upgrade-shared command

[mayeut]

• I have added a news fragment under changelog.d/ (if the patch affects the end users)

Summary of changes

Add upgrade-shared command

This allows to create/upgrade shared libraries as a standalone command.

It might be useful to initialize shared libraries with a pinned version of pip in order to create e.g. reproducible docker images using a constraint file.

It also allows for different --pip-args that one would get with the install command.

Test plan

Tested in tests/test_upgrade_shared.py

[chrysle]

Thank you for doing this! Could you extend our documentation at how-pipx-works.md, stating clearly how the shared libs can be upgraded?

[mayeut]

@chrysle, I'm not sure what to add to how-pipx-works.md. I added an example though.

[chrysle]

I'm not sure what to add to how-pipx-works.md.

I thought of adding something like "This [shared lib] can later on be managed with the upgrade-shared command" at the bullet point introducing the shared libs concept. Might be unnecessary.

I added an example though.

Looks good, thanks! We somehow ignored it for a while, but there is a certain scripts/gen_doc_pages.py script that takes care of filling the template for our command line documentation (https://pipx.pypa.io/stable/docs/). Could you amend that? And, please split the commit updating the test packages into another PR, since it feels unrelated.

[mayeut]

Could you amend that?

Done

And, please split the commit updating the test packages into another PR, since it feels unrelated.

It's related but I limited the update to what's necessary only (pip).

[chrysle]

I'm completely baffled by this. It can't be that quoted dependency specifiers containing spaces are disrespected on Windows only?

[mayeut]

just fixed conflicts with the main branch

[chrysle]

Thanks, @mayeut!