update workflow to test master

Author: ricardochaves

.github/workflows/workflow.yml

@@ -8,6 +8,6 @@ jobs:
 
     steps:
       - uses: actions/checkout@v1
-      - uses: ricardochaves/python-lint@test
+      - uses: ricardochaves/python-lint@master
         with:
           python-root-list: "tests"