Preview deployments created by CI for pull requests are never deleted

[aperezdc]

Currently every time a new build is done by the continuous integration for a pull request (using .github/workflows/pr.yml) creates a deployment directory with the same name as the source branch of the pull request and pushes it to be published using GitHub Pages, but those are never deleted afterwards.

Ideally, we would delete the preview deployments once a pull request is closed and the source branch of the pull request has been deleted.

This fix would be nice to have, but definitely low priority 💆

[septatrix]

GitHub is also working on a preview feature for GH pages. It is still in development (and sadly has been so for a while) but we could just sit it out and wait for it to become generally available (currently it is available for GH's own repos only)

In #268 it also seems like the change is not applied?