Update sphinx to 1.7.7

[pyup-bot]

This PR updates Sphinx from 1.7.6 to 1.7.7.

Changelog

1.7.7

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

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

* 5198: document not in toctree warning when including files only for parallel
builds
* LaTeX: reduce "Token not allowed in a PDF string" hyperref warnings in latex
console output (refs: 5236)
* LaTeX: suppress "remreset Warning: The remreset package is obsolete" in latex
console output with recent LaTeX (refs: 5237)
* 5234: PDF output: usage of PAPER environment variable is broken since Sphinx
1.5
* LaTeX: fix the :confval:`latex_engine` documentation regarding Latin Modern
font with XeLaTeX/LuaLateX (refs: 5251)
* 5280: autodoc: Fix wrong type annotations for complex typing
* autodoc: Optional types are wrongly rendered
* 5291: autodoc crashed by ForwardRef types
* 5211: autodoc: No docs generated for functools.partial functions
* 5306: autodoc: ``getargspec()`` raises NameError for invalid typehints
* 5298: imgmath: math_number_all causes equations to have two numbers in html
* 5294: sphinx-quickstart blank prompts in PowerShell

Links

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