Only publish on new tag pushed

.github/workflows/pypi.yml

@@ -1,13 +1,11 @@
 name: pypi-publish
 on:
   push:
-    branches: [ master ]
     tags:
       - 'v*'
 jobs:
   publish:
     runs-on: ubuntu-latest
-    if: startsWith(github.ref, 'refs/tags/v')
     steps:
     - uses: actions/checkout@v2
     - name: Set up Python