Use GitHub Actions for CI

[pjsier]

We've had some success with GitHub Actions instead of Travis CI on the other City Scrapers projects, so I wanted to add it as a suggestion here.

Some benefits:

• Better integration into GitHub's UI for finding test failures (here's an example of a failing test)
• More generous free tier for open source projects, including a max of 6 hours for running jobs
• More control over cron jobs (Travis CI only allows you to set how often a job occurs, but GitHub Actions lets you set a specific time with a cron expression)

It's currently failing because of a dependency issue that will be fixed in #81

[pjsier]

One thing I noticed is that it looks like a lot of the scrapers aren't outputting correctly because "id" and "status" aren't included in the output. The ValidationPipeline output in the CI doesn't throw an error for this, but it does show the results