Update and rename python-app.yml to flake8-pytest.yml

Be more explicit with workflow naming

.github/workflows/python-app.yml → .github/workflows/flake8-pytest.yml

@@ -1,7 +1,7 @@
-# This workflow will install Python dependencies, run tests and lint with a single version of Python
+# This workflow will install Python dependencies, run tests and lint with a matrix of Python versions
 # For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-python
 
-name: Python application
+name: Flake8 and Pytest
 
 on:
   push: