Validate types of action inputs

[krzema12]

Act version

0.2.66

Feature description

Hi!

I thought that a nice addition to the tool would be the ability to validate if given values of inputs match the declared inputs. You may think "but the actions don't really declare the types". Indeed, GitHub doesn't let action owners define the types with a first-party tool, but there's:

• typesafegithub/github-actions-typing - an emerging standard for defining the typings. Several dozens of actions already host action-types.yml in their repos!
• typesafegithub/github-actions-typing-catalog - whenever it's not possible to host the typings in the action's repo, there's this catalog where everyone can contribute the typings

Integrating with the above tools would let the users know about a type mismatch even before actually running the workflow. I thought it could be an opt-in feature, so that by default, GitHub's behavior of not checking the types is preserved. Alternatively, opt-out would help with giving the users more safety by default, and they could disable if needed.

Let me know what you think!