Modify `.github/workflows/cetlvast.yml` to accept (in addition to `main`) also `issue/*` branches.

[serges147]

The idea is to have for relatively big features/issues a "stable" buildable staging branch - where multiple consecutive the feature/issue-related PRs could be targeted - before the final merge to the main when everything is done - something similar to the git flow process. It's desirable that such issue/* branches will be automatically built by our git hub actions.

There is also proposition to establish minimal convention for such branch names, like:issue/NN_LABEL, where

• NN is github issue number
• LABEL very minimal human friendly string giving context of the issue, like f.e. issue/83_any.

[thirtytwobits]

Yeah +1. Like this idea.