workflow: keep running on failures

By default GitHub will cancel the remaining jobs if at least one fails.
Disable this behaviour to maximize the test visibility.

Author: jkloetzke

Diff for: .github/workflows/workflow.yaml

@@ -8,6 +8,7 @@ jobs:
         strategy:
             matrix:
                 python-version: [3.6, 3.7, 3.8, 3.9]
+            fail-fast: false
 
         steps:
             - name: Checkout