Don't require to press `Enter` after entering workflow name

[bartekpacia]

This is a small suggestion for a QoL improvement.

$ melos run
Select a script to run in this workspace:

1) lint:all
    └> Run all static analysis checks.
2) analyze
    └> Run `flutter analyze` for all packages.
3) format
    └> Run `dart format` checks for all packages.
4) test
    └> Run `flutter test` for selected packages.


? Enter your choice 

After entering 1, the lint:all workflow doesn't start executing - instead, I have to press the Enter key. I wish it wasn't required.

(If there are than 9 workflows, the Enter would be still required).

[Salakar]

This behavior comes from the cli prompting library - I'm not sure if it allows configuring the enter key behavior, if you have time to figure it out though I'd happily accept & merge a PR 😄