Bumping actions/core and actions/github dependencies for GHES

[pjquirk]

This adds support for running against GHES by using v2.2.0 of @actions/github. I also bumped @actions/core to 1.2.4 to fix error handling in the case an Error type is thrown rather than a string.

The build/pack steps seemed unreliable, so I updated the Typscript config to build to ./lib, and ncc will then build out of that (this matches other actions like actions/stale).

Tested by pushing this version of the action to an "actions" org on the GHES instance. I also needed to set NODE_TLS_REJECT_UNAUTHORIZED = 0 temporarily in the action to get around my self-signed (or otherwise not trusted) server cert.

[dakale]

What is the benefit of changing from dist/index to lib/index? Not sure I understand the point, or why the lib/ file is so much smaller than the dist/ one...

[pjquirk]

@dakale It's mainly to distinguish the outputs of tsc (lib) and the outputs of ncc (dist). It doesn't make sense to put them both into the same folder, like it was before. dist should have one file in it, index.js.

[dakale]

Thanks, that makes sense, as does ignoring checking in lib/

[dakale]

(I can merge if you dont have permission)