Build containers for pushes to main and only published releases

[webbnh]

Given that the Action for building containers is fairly intelligent about how it tags them, there is no reason not to build and publish containers for pushes to the main branch. Also, creating a single release goes through four different states, and there is no reason to trigger a container build on every one of them for a single release.

So, this PR adds main to the list of branches for which we build containers and it pares the list of release states down to just published.

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (c6492c6) 98.52% compared to head (d244c7f) 98.52%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #13   +/-   ##
=======================================
  Coverage   98.52%   98.52%           
=======================================
  Files           2        2           
  Lines         541      541           
=======================================
  Hits          533      533           
  Misses          8        8           

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[dbutenhof]

So we don't want to build a container image on a draft release? I suppose it really doesn't matter much.

[webbnh]

So we don't want to build a container image on a draft release?

I told myself that, before we create a release, we must have pushed to main at least once (which should now create a container image), and we probably created a tag (which will create another container image), so there should be adequate availability for pre-release testing. (And, to be honest, I'm not even sure which user actions correspond to which triggers. 😝)