Update publish.yml - fix branch name

Author: kategengler

.github/workflows/publish.yml

@@ -26,7 +26,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
-          ref: 'master'
+          ref: 'main'
       # This will only cause the `check-plan` job to have a result of `success`
       # when the .release-plan.json file was changed on the last commit. This
       # plus the fact that this action only runs on main will be enough of a guard