Update hypothesis to 6.13.13

[pyup-bot]

This PR updates hypothesis from 6.13.9 to 6.13.13.

Changelog

6.13.13

--------------------

This patch teaches :doc:`the Ghostwriter <ghostwriter>` how to find
:np-ref:`custom ufuncs <ufuncs.html>` from *any* module that defines them,
and that ``yaml.unsafe_load()`` does not undo ``yaml.safe_load()``.

6.13.12

--------------------

This patch reduces the amount of internal code excluded from our test suite's
code coverage checks.

There is no user-visible change.

6.13.11

--------------------

This patch removes some old internal helper code that previously existed
to make Python 2 compatibility easier.

There is no user-visible change.

6.13.10

--------------------

This release adjusts some internal code to help make our test suite more
reliable.

There is no user-visible change.

Links

• PyPI: https://pypi.org/project/hypothesis
• Changelog: https://pyup.io/changelogs/hypothesis/
• Homepage: https://hypothesis.works