Update sphinx to 1.6.2

[pyup-bot]

There's a new version of Sphinx available.
You are currently using 1.6.1. I have updated it to 1.6.2

These links might come in handy: PyPI | Changelog | Homepage

Changelog

1.6.2

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

Incompatible changes

• 3789: Do not require typing module for python>=3.5

Bugs fixed

• 3754: HTML builder crashes if HTML theme appends own stylesheets
• 3756: epub: Entity 'mdash' not defined
• 3758: Sphinx crashed if logs are emitted in conf.py
• 3755: incorrectly warns about dedent with literalinclude
• 3742: RTD <https://readthedocs.org/>_ PDF builds of Sphinx own docs are
  missing an index entry in the bookmarks and table of contents. This is
  rtfd/readthedocs.org2857 <https://github.com/rtfd/readthedocs.org/issues/2857>_ issue, a workaround
  is obtained using some extra LaTeX code in Sphinx's own :file:conf.py
• 3770: Build fails when a "code-block" has the option emphasize-lines and the
  number indicated is higher than the number of lines
• 3774: Incremental HTML building broken when using citations
• 3772: 'str object' has no attribute 'filename'
• 3763: got epubcheck validations error if epub_cover is set
• 3779: 'ImportError' in sphinx.ext.autodoc due to broken 'sys.meta_path'.
  Thanks to Tatiana Tereshchenko.
• 3796: env.resolve_references() crashes when non-document node given
• 3803: Sphinx crashes with invalid PO files
• 3791: PDF "continued on next page" for long tables isn't internationalized
• 3788: smartquotes emits warnings for unsupported languages
• 3807: latex Makefile for make latexpdf is only for unixen
• 3781: double hyphens in option directive are compiled as endashes
• 3817: latex builder raises AttributeError

Got merge conflicts? Close this PR and delete the branch. I'll create a new PR for you.

Happy merging! 🤖