remove unnecessary dependencies, doc from tests workflow

Author: melonora

.github/workflows/tests.yml

@@ -25,5 +25,3 @@ jobs:
         run: pip install -e ".[dev]"
       - name: Test code's execution (pytest)
         run: pytest -v tests
-      - name: Test docs' building (Sphinx)
-        run: python -m sphinx -b html docs docs/_build