Introduce pipx pin and pipx unpin commands

[dukecat0]

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

Summary of changes

Introduce pipx pin and pipx unpin commands, which can be used to pin or unpin the version
of an installed package, so it will not be upgraded by pipx upgrade or pipx upgrade-all.

Closes #891
Closes #802

Test plan

Tested by running

nox -s tests-3.12

[chrysle]

Thanks for submitting this! I wonder whether it would be a valid use case to extend this behaviour to work with injected packages, too?

Another idea: Provide protection from removal for a pipx-installed package by pipx pin via an option.

[dukecat0]

I wonder whether it would be a valid use case to extend this behaviour to work with injected packages, too?

That sounds like a good idea! Probably I will add a new option for it.

Another idea: Provide protection from removal for a pipx-installed package by pipx pin via an option.

Not sure if it's a common usage, but we can add it in the future if there are requests about this.

[dukecat0]

I wonder whether it would be a valid use case to extend this behaviour to work with injected packages, too?

I am implementing the logic of --injected-packages-only and it will only pin injected packages only instead of main package. (As running pipx pin <package> should prevent both main package and injected packages from upgrading during pipx upgrade-all --include-injected.)

[chrysle]

I am implementing the logic of --injected-packages-only and it will only pin injected packages only instead of main package.

Sounds good. You don't think one should be able to select which injected package to work with?

[dukecat0]

Yes, forgot to mention it in the above comment. 😅 I will mark this PR as draft first.

[dukecat0]

The failed test seems unrelated to this PR.

[huxuan]

The failed test seems unrelated to this PR.

Rerun makes everything OK. :-)