Re-enable release detection workflow

[riccardoporreca]

The Detect release workflow is currently disabled

This scheduled workflow is disabled because there hasn't been activity in this repository for at least 60 days. Enable this workflow to resume scheduled runs.

As a consequence, the recent 4.x releases were not built

Besides this, it looks like https://quay.io/repository/hugoguru/html-proofer has been replacing https://hub.docker.com/r/klakegg/html-proofer as the Docker image repository: is there a way to mark this in https://hub.docker.com/r/klakegg/html-proofer pointing to the new one for versions >= 3.19.2? I guess this should be also suggested in the HTMLProofer README

[metbril]

This could easily be prevented with a workflow using an action like this

https://github.com/marketplace/actions/keepalive-workflow