Find alternative to click-completion which is now in maintenance mode

[matthewfeickert]

As https://github.com/click-contrib/click-completion

is in maintenance mode only. No new features will be added.

an alternative should be found so that it can be migrated away from. At the moment it is only used in the

pyhf/pyproject.toml

Line 69 in 35acce8

shellcomplete = ["click_completion"]

extra, so there is a low impact on pyhf as a project overall.

[matthewfeickert]

Also noticed in #2638 (comment):

there is a native Click v8 completion. c.f. https://click.palletsprojects.com/en/stable/shell-completion/#shell-completion

[matthewfeickert]

@kratsg I find https://click.palletsprojects.com/en/stable/shell-completion slightly confusing about what specifically would need to happen for pyhf to use this. Do you understand and can you give a simple example?