enhancement: implement Coverity check prior to each release

[perkelix]

Here is an example from another project:

https://github.com/ipxe/ipxe/blob/master/.github/workflows/coverity.yml

Ffor that particular case, branch synchronisation is handled by a cron job running somewhere, but could easily be done by a scheduled GitHub action instead.

[rsmarples]

I have no objection to this. I have a lot going on in my personal life right now and won't be able to look at this for a week or so.