Consider automating deploys to WordPress from Github Actions

[NielsdeBlaauw]

Let's see if we can automate publishing tags to the WordPress plugin repository. It's fairly simple using GitHub actions and a preset action like 10-up's plugin deployment.

Automating this step would allow us to add build steps and quality control. This allows issues like #26 and #16, and makes it possible to add tools like wpcs.

I have some experience implementing GH Actions, and would love to help work this out. What do you think @yehudah?