CI: Fix Codecov uploader by using GitHub Action recipe

Author: amotl

.github/workflows/test.yml

@@ -32,5 +32,11 @@ jobs:
       - name: Run tests
         run: |
           coverage run --source grafana_client -m xmlrunner discover -o test-reports
-          codecov
+          coverage xml
         shell: bash
+
+      # https://github.com/codecov/codecov-action
+      - name: Upload coverage results to Codecov
+        uses: codecov/codecov-action@v2
+        with:
+          fail_ci_if_error: true

.gitignore

@@ -41,6 +41,7 @@ pip-log.txt
 pip-delete-this-directory.txt
 
 # Unit test / coverage reports
+test-reports/
 htmlcov/
 .tox/
 .coverage