Update sphinx to 3.0.3

[pyup-bot]

This PR updates Sphinx from 3.0.1 to 3.0.3.

Changelog

3.0.3

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

Dependencies
------------

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

Deprecated
----------

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

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

Testing
--------

3.0.2

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

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

* C, parse attributes and add :confval:`c_id_attributes`
and :confval:`c_paren_attributes` to support user-defined attributes.

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

* 7461: py domain: fails with IndexError for empty tuple in type annotation
* 7510: py domain: keyword-only arguments are documented as having a default of
None
* 7418: std domain: :rst:role:`term` role could not match case-insensitively
* 7461: autodoc: empty tuple in type annotation is not shown correctly
* 7479: autodoc: Sphinx builds has been slower since 3.0.0 on mocking
* C++, fix spacing issue in east-const declarations.
* 7414: LaTeX: Xindy language options were incorrect
* sphinx crashes with ImportError on python3.5.1

Links

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

[pyup-bot]

Closing this in favor of #67