Fix GitHub action

Author: jochenklar

.github/workflows/main.yml

@@ -31,7 +31,7 @@ jobs:
   deploy:
     runs-on: ubuntu-latest
     needs: build
-    if: github.ref == 'refs/heads/master'
+    if: github.ref == 'refs/heads/main'
     steps:
     - name: Download artifact
       uses: actions/download-artifact@v2