Fix branch check in publish.yml

Author: pederhan

.github/workflows/publish.yml

@@ -16,8 +16,9 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      # https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/accessing-contextual-information-about-workflow-runs#determining-when-to-use-contexts
       - name: Exit if not on master branch
-        if: github.ref_name != 'master'
+        if: ${{ github.ref == 'refs/heads/main' }}
         run: exit -1
 
       - name: Install uv