Remove python 3.9 build for now

Author: gonzalocasas

.github/workflows/build.yml

@@ -14,15 +14,11 @@ jobs:
     strategy:
       matrix:
         name: [
-          "ubuntu-py39",
           "windows-py38",
           "macos-py37",
           "ubuntu-py36",
         ]
         include:
-          - name: "ubuntu-py39"
-            os: ubuntu-latest
-            python-version: 3.9
           - name: "windows-py38"
             os: windows-latest
             python-version: 3.8