Fix Coveralls workflow

Fix the integration between coverage and coveralls, and respect Pipfile.lock

.github/workflows/test.yaml

@@ -25,10 +25,14 @@ jobs:
         with:
           python-version: 3.8
       - run: pip install -U pipenv
-      - run: pipenv install --dev
+      - run: pipenv sync --dev
       - run: pipenv run coverage run -m pytest tests/ -svv
+      - run: pipenv run coverage lcov
       - name: upload coverage to coveralls
         uses: coverallsapp/github-action@v2
+        with:
+          file: coverage.lcov
+          fail-on-error: false
 
   sam-build-and-lint:
     runs-on: ubuntu-latest