Converting Travis to GitHub Actions

After the weekly runs this week, I plan to execute a script that will automatically convert all weekly-tagged repos to GitHub Actions from Travis. The script will remove .travis.yml files and add .github/workflows/*.yaml files in two commits on master.

Similar to tech notes moving, speed and reliability should improve. In addition, thanks to branch protections that will also be imposed, the “big green button” on GitHub will be safely usable to merge pull requests for all such repos. The Dev Guide will be updated to reflect this.

The templates have already been changed so that newly-created repos should use GitHub Actions from the beginning.

Only tagged repos are being changed to avoid the large number of third-party dependency repos, documents that have already been converted, and other unusual cases.

Please let me know if you experience any problems or notice anything unusual.

This is now done. Replacing Travis for lsst and lsst_build and the SCons* checks for ci_hsc_gen2/3 will come later.