add alias to auto_req for disabled option

[Will-Shanks]

Adding a no alias to auto-req for the disabled option to reverse a regression made as part of #82 see #101 for details.

> #before 
> cargo run --release -- --auto-req no
error: invalid value 'no' for '--auto-req <AUTO_REQ>'
  [possible values: disabled, builtin, find-requires, /path/to/find-requires]

For more information, try '--help'.

> #after
> cargo run --release -- --auto-req no
>

[cat-in-136]

Thanks a lot.