Transition this library from Travis to GitHub Action

[Alexander Entinger]

Since the new GitHub Actions CI build system obviously is the way to go I'd like to transition this repository to the new system. @per1234 can I ask you to do that?

[per1234]

No problem.

Some questions:

• Do you want size deltas reports?
• Do you want size trends reports?
• If yes to either of the above, which example should be the "size report sketch"?

[Alexander Entinger]

Hi 👋

Do you want size deltas reports?

Yes.

Do you want size trends reports?

I'd like to wait if/when the history over master feature is available, so no for now.

If yes to either of the above, which example should be the "size report sketch"?

Please use this sketch.

Thank you 🚀