Install docs dependencies from pyproject in github workflow

.github/workflows/sphinx_docs_to_gh_pages.yaml

@@ -20,8 +20,7 @@ jobs:
  run: |
  sudo apt install pandoc
  python -m pip install --upgrade pip
- pip install .
- pip install -r docs/requirements.txt
+ pip install .[docs]
  - name: Build the docs
  run: |
  cd docs