Add poetry check

.github/workflows/python-package.yml

@@ -1,6 +1,3 @@
-# This workflow will install Python dependencies, run tests and lint with a variety of Python versions
-# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-python
-
 name: Python package
 
 on:
@@ -29,12 +26,13 @@ jobs:
         python -m pip install --upgrade pip
         python -m pip install flake8 pytest poetry
         if [ -f pyproject.toml ]; then poetry install; fi
+    - name: Check if lock file is up-to-date
+      run: |
+        poetry check
     - name: Lint with flake8
       run: |
-        # stop the build if there are Python syntax errors or undefined names
         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: Test with pytest
       run: |
-        pytest
+        pytest