Add version command to CLI

[whoabuddy]

I mentioned it in Discord then thought it'd be a fun one to tackle and learn a little more about contributing to Python projects.

Example usage:

$ crewai version
crewai version: 0.22.5

$ crewai version --tools
crewai version: 0.22.5
crewai tools version: 0.22.5

Help text:

$ crewai --help
Usage: crewai [OPTIONS] COMMAND [ARGS]...

  Top-level command group for crewai.

Options:
  --help  Show this message and exit.

Commands:
  create   Create a new crew.
  version  Show the installed version of crewai.

$ crewai version --help
Usage: crewai version [OPTIONS]

  Show the installed version of crewai.

Options:
  --tools  Show the installed version of crewai tools
  --help   Show this message and exit.

I added a test as well, lmk if anything else needs to be updated, didn't touch readme or docs as so many things are in motion 😉