Update to build the package only on commit to master.

We don't build at other times.

Author: gerph

.github/workflows/ci.yml

@@ -32,10 +32,12 @@ jobs:
           make tests
 
       - name: Build package
+        if: github.ref == 'refs/heads/master'
         run: |
           make package
 
       - uses: actions/upload-artifact@v6
+        if: github.ref == 'refs/heads/master'
         with:
           name: Package
           path: dist