Only run legacy appveyor ci on github master branch

[xnorpx]

WIP, don't apply this patch yet......

[jmvalin]

Actually, the only reason there's still a master branch is that I haven't found a way to delete it. I already deleted it on gitlab.xiph.org. Any idea how to also delete it on the github mirror?

[xnorpx]

@jmvalin ah that's even better.

Based on the documentation, you should be able to delete it once you changed the default branch.

But maybe you need to close all PR's that still pointing to master?

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/creating-and-deleting-branches-within-your-repository

Maybe close all open PR's that points to master and ask the authors to reopen against main if they still are relevant and interested.

If the branch you want to delete is associated with an open pull request, you must merge or close the pull request before deleting the branch.

It also looks like there is 3 commits' on master that is not on main if they are still relevant in any way.

[xnorpx]

Closing as master branch will be removed (once it's known how to)

[jmvalin]

Well, I think I found how to delete it. Side effect is that I think it just closed all PRs for master

[xnorpx]

Well, I think I found how to delete it. Side effect is that I think it just closed all PRs for master

Good to clean house :)

Master branch is deleted and all pr's against master is closed. If this change is still relevant please reopen and repoint your PR to main branch.

[mark4o]

These open PRs were automatically closed when the "master" branch was deleted: #109, #143, #153, #187, #210, #233, #250, #257, #262, #285, #304. Those that are still relevant should be rebased against the "main" branch instead of "master" and reopened.