--version flag no longer exists

[lopopolo]

Describe the bug
I have been invoking cargo-about --version to check whether cargo-about is installed in a script before kicking off a cargo install cargo-about only if it is required.

It appears the --version flag no longer exists

To Reproduce

$ cargo about --version
error: Found argument '--version' which wasn't expected, or isn't valid in this context

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

USAGE:
    cargo-about [OPTIONS] <SUBCOMMAND>

For more information try --help
$ cargo-about --version
error: Found argument '--version' which wasn't expected, or isn't valid in this context

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

USAGE:
    cargo-about [OPTIONS] <SUBCOMMAND>

For more information try --help
$ cargo about -- --version
error: Found argument '--version' which wasn't expected, or isn't valid in this context

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

USAGE:
    cargo-about [OPTIONS] <SUBCOMMAND>

For more information try --help
$ cargo-about -- --version
error: Found argument '--version' which wasn't expected, or isn't valid in this context

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

USAGE:
    cargo-about [OPTIONS] <SUBCOMMAND>

For more information try --help

Expected behavior

cargo about --version and cargo-about --version output the version of the executable and exit with a success status code.

[lopopolo]

I suspect #178 is implicated in this regression, but I have not bisected.

[Jake-Shadle]

Yes you are correct, clap doesn't automatically add version/author etc metadata like structopt does.