Convert from Travis CI to GitHub Actions

[geerlingguy]

Travis kinda left open source maintainers out in the dust with their new pricing plan this week, so I'm going to transition this role (and all my others) to GitHub Actions, since I should be able to get CI done there still.

[geerlingguy]

Related: Support any CI-server for notifications

[geerlingguy]

The most annoying part of this is having to release and add a GALAXY_API_KEY secret to my GitHub repositories. You can't add a secret at the profile level (only organization or repo level), so I'm going to have to write up some automation to run through all my repositories and add that secret so I can still auto-publish new tags to Galaxy.

[geerlingguy]

I think I might write a script using PyGithub to loop through all my repositories and create a Secret for GitHub actions in each one using the code in this PR that adds secret support.

[geerlingguy]

I created github-repo-manager, and I used it to add a GALAXY_API_KEY secret to each of the geerlingguy/ansible-role-* repositories in my account.

Yay, that wasn't super annoying. But getting all the projects updated to use actions will be :P

[geerlingguy]

Merging the PR and I'm going to test tagging a new release to see if it correctly triggers a Galaxy import...