Support GHES

[marikaner]

Hi, your action seems like it is doing exactly what I would need, but I can't use it because it won't work with GHES as github.com is the hardcoded server url. It would be great to consider this, similar to the checkout action.

[ad-m]

@marikaner could you consider provider PR to add support for that?

[ad-m]

I don't have unfortunately access to any GHES environment to develop feature like that.