Do not offer --version on subcommands

[itowlson]

Fixes #83.

As noted on that issue, before merging this we should understand the intent behind having the propagate_version flag there in the first place. @kate-goldenring git blame has your name on the commit, though I think several people contributed to that first cut - do you know why this was set?

Before:

$ spin cloud variables -V
spin-cloud-variables 0.2.0 (78c325a 2023-09-14)

After:

$ spin cloud variables -V
error: Found argument '-V' which wasn't expected, or isn't valid in this context

        If you tried to supply `-V` as a value rather than a flag, use `-- -V`

USAGE:
    spin cloud variables <SUBCOMMAND>

For more information try --help

# Still works on top-level command
$ spin cloud -V
spin-cloud 0.2.0 (78c325a 2023-09-14)

[kate-goldenring]

@itowlson I am not sure why i added it and this is surely needed removed. Thank you!