Update sphinx to 3.1.1

[pyup-bot]

This PR updates sphinx from 3.1.0 to 3.1.1.

Changelog

3.1.1

=====================================

Incompatible changes
--------------------

* 7808: napoleon: a type for attribute are represented as typed field

Features added
--------------

* 7807: autodoc: Show detailed warning when type_comment is mismatched with its
signature

Bugs fixed
----------

* 7808: autodoc: Warnings raised on variable and attribute type annotations
* 7802: autodoc: EOFError is raised on parallel build
* 7821: autodoc: TypeError is raised for overloaded C-ext function
* 7805: autodoc: an object which descriptors returns is unexpectedly documented
* 7807: autodoc: wrong signature is shown for the function using contextmanager
* 7812: autosummary: generates broken stub files if the target code contains
an attribute and module that are same name
* 7808: napoleon: Warnings raised on variable and attribute type annotations
* 7811: sphinx.util.inspect causes circular import problem

Links

• PyPI: https://pypi.org/project/sphinx
• Changelog: https://pyup.io/changelogs/sphinx/
• Homepage: http://sphinx-doc.org/