build(python): fix `docs` and `docfx` builds#319

Genesis929 merged 4 commits intomaingoogleapis/python-bigquery-dataframes:mainfrom

owl-bot-update-lock-5ea6d0ab82c956b50962f91d94e206d3921537ae5fe1549ec5326381d8905cfagoogleapis/python-bigquery-dataframes:owl-bot-update-lock-5ea6d0ab82c956b50962f91d94e206d3921537ae5fe1549ec5326381d8905cfaCopy head branch name to clipboard