Fix codecov in PR branches (#6)

Author: nbara

.github/workflows/pythonpackage.yml

@@ -37,7 +37,6 @@ jobs:
       run: |
         pytest --cov=meegkit --cov-report=xml tests/
     - name: Upload coverage to Codecov
-      env:
-        CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
-      run:
-        codecov -t ${CODECOV_TOKEN}
+      uses: codecov/codecov-action@v1
+      with:
+        fail_ci_if_error: false # optional (default = false)