Use pytest to generate coverage

.github/workflows/python-package.yml

@@ -33,6 +33,6 @@ 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: Test with unittest
+    - name: Test with pytest
       run: |
-        python3.10 -m unittest discover tests
+        python3.10 -m pytest --cov=calculator tests/

.gitlab-ci.yml

@@ -5,7 +5,8 @@ cache:
 
 before_script:
   - python -V
+  - python -m pip install --upgrade pytest pytest-cov 
 
 tests:
   script:
-    - python -m unittest discover tests
+    - python -m pytest --cov=calculator tests/