Support for custom values in contexts

[thepeak99]

First of all I'd like to say, amazing tool! It saves me a lot of time and pain by being able to test things locally, instead of having to do a zillion test commit/push cycles 😄 🙏.

I am basically looking for a way to specify fake values to these vars: https://docs.github.com/en/free-pro-team@latest/actions/reference/context-and-expression-syntax-for-github-actions#contexts

Concretely I am looking for github.repository_owner, but a generic way to specify any of those would be awesome.

[github-actions[bot]]

Issue is stale and will be closed in 7 days unless there is new activity

[rubenflamshepherd]

I know this issue is stale but if I could give it a quick bump, amazing tool and this feature request would put it over the top!