Updating workflow to include python 3.9

Author: ctralie

.github/workflows/python-publish.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.6, 3.7, 3.8, 3.9]
 
     runs-on: "ubuntu-latest"
     steps:
@@ -43,7 +43,7 @@ jobs:
       fail-fast: false
       matrix:
         arch: ['x86', 'x64']
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.6, 3.7, 3.8, 3.9]
 
     runs-on: "windows-latest"