Update pythonpackage.yml

Author: AtsushiSakai

.github/workflows/pythonpackage.yml

@@ -28,5 +28,7 @@ jobs:
         flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
         # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
         flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
+    - name: install coverage
+      run: pip insall coverage   
     - name: Test
       run: bash runtests.sh