Prevent CI action running on both master and gh-pages branches

[SiAdcock]

Describe the bug
Currently the CI action runs on both master and gh-pages branches. This is unnecessary

Expected behavior
Only the Deploy to GitHub Pages action should run on master. We don't need any actions to run explicitly on gh-pages.

[JamieB-gu]

Is it this line that you're talking about here?

source/.github/workflows/ci.yml

Line 5 in 0b9bcee

- "*"

[SiAdcock]

Yeah. So I want the CI workflow to run only on branches that are not called master or gh-pages. Is that possible, do you know? My regex / globby skills failed me!

[JamieB-gu]

Based on my reading of the docs, I think that PR should do it.