Move from Travis CI to GitHub Actions

[jpdillingham]

Travis CI discontinued their free product, which this relies (relied?) on. Either way, CI is broken and will remain that way.

We should use GitHub Actions for CI, instead.

I can help by adding whatever environment variables we need.

[Udeozor]

Hello, I would like to take this up.

[jpdillingham]

Thanks! I'll go ahead and generate new AWS credentials and put them in environment variables for you.

[jpdillingham]

You can find the AWS creds in AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY. These creds belong to the same user we were using for Travis CI, and permissions are unchanged (S3 full access) so there should be no issue uploading code or setting the ACL, but let me know if you encounter any issues.