Update python-publish.yml

Author: jhavl

.github/workflows/python-publish.yml

@@ -16,7 +16,7 @@ jobs:
       max-parallel: 2
       matrix:
         os: [macos-latest, windows-latest]
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.6, 3.7, 3.8, 3.9]
 
     steps:
     - uses: actions/checkout@v2