AWS Upload workflow should recognise that master and main are both default branches in repos

[mfitz]

There is some logic in the AWS Upload workflow that creates a file called release_name if the triggering push is for a non-default branch, which is determined by checking the branch name against refs/heads/main.

Some older repos still use refs/heads/master as the default branch name (the previous default in GitHub), so the conditional should also include a check against that name.

[KasiaKoz]

How about, instead of main and master, we introduce a variable that defaults to main and can be configured if the repo has a different default branch?

[mfitz]

How about, instead of main and master, we introduce a variable that defaults to main and can be configured if the repo has a different default branch?

Yep, that works. You can crib that from this previous PR.

[mfitz]

There's also a variable in GitHub Actions that looks like it gives you the default branch name @KasiaKoz. I haven't tried this, but look into it; if it works, that's the cleanest solution, I think.