Add test suite to CI

[timcallow]

Attempting to add test suite to CI. Let's see how it goes...

[DanielKotik]

LGTM, but I would suggest to put the test workflow in an extra YAML file in the .github/workflows/ folder. Maybe call it just tests.yml. Then its logically separated from the the workflow for building and deploying the Sphinx documentation deployed at GitHub pages (gh-pages.yml). This comes also with more fine control about when the tests should be triggered (can of course be identical with when docs are triggered). Start test.yml with

name: docs
on:
  pull_request:
    branches:
      - master
      - develop
  push:
    branches:
      - master
      - develop
jobs:
  run-test-suite
  ...