Wrap shell completion command in if statement

[oliverralbertini]

Was discussed in this issue: #166

[tony]

@ohardy Hi there, sorry about this! Can I get a rebase?

I just merged #623 which moves us to a poetry packaging setup and will runs the PR through GitHub actions.

[tony]

@oliverralbertini Hi there, sorry about this! Can I get a rebase?

I just merged #623 which moves us to a poetry packaging setup and will runs the PR through GitHub actions.

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[tony]

@oliverralbertini Sorry, I have let this PR sit too long. That is my fault

I haven't looked into autocompletion in some time, but if you wanted to make a new PR, it'd be to here: https://github.com/tmux-python/tmuxp/blob/master/docs/cli.md

I will close this for now as it's diverged too far and there hasn't been any rebases or pings since, but if you'd like to make a new PR for this please do.