Disable fail-fast for the moment, it makes debugging slightly easier.

.github/workflows/pythonpackage.yml

@@ -10,6 +10,7 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
         python-version: [3.6, 3.7, 3.8, pypy3]
+      fail-fast: false
 
     steps:
     - uses: actions/checkout@v2