Add --version swich to top-level nitpick command

[mjpieters]

Problem

I can't, from the command line, determine what version of nitpick has been installed. Instead, I have to first determine how the tool was installed (homebrew, pipx, pip, yay?) then query the installer tool for metadata.

This makes it a lot harder to document how to gather troubleshooting information when supporting someone else using nitpick in a larger organisation.

Possible solution

Please add a nitpick --version command-line option that shows what exact version you are running.

[andreoliwa]

Fixed by #468