Update decorator to 5.0.9

[pyup-bot]

This PR updates decorator from 4.2.1 to 5.0.9.

Changelog

5.0.9

Fixed a test breaking PyPy. Restored support for Sphinx.

5.0.8

Made the decorator module more robust when decorating builtin functions
lacking dunder attributes, like `dict.__setitem__`.

5.0.7

The decorator module was not passing correctly the defaults inside the
`*args` tuple, thanks to Dan Shult for the fix. Also fixed some mispellings
in the documentation and integrated codespell in the CI, thanks to 
Christian Clauss.

5.0.6

The decorator module was not copying the __module__ attribute anymore. Thanks to
Nikolay Markov for the notice.

5.0.5

Dropped support for Python < 3.5 with a substantial simplification of
the code base (now building a decorator does not require calling "exec").
Added a way to mimic functools.wraps-generated decorators.
Ported the Continuous Integration from Travis to GitHub.

4.4.2

Sylvan Mosberger (https://github.com/Infinisil) contributed a patch to
some doctests that were breaking on NixOS.
John Vandenberg (https://github.com/jayvdb) made a case for removing the usage
of `__file__`, that was breaking PyOxidizer.
Miro Hrončok (https://github.com/hroncok) contributed some fixes for the
future Python 3.9.
Hugo van Kemenade (https://github.com/hugovk) contributed some fixes for the
future Python 3.10.

4.4.1

Changed the description to "Decorators for Humans" are requested by
several users. Fixed a .rst bug in the description as seen in PyPI.

4.4.0

Fixed a regression with decorator factories breaking the case with no
arguments by going back to the syntax used in version 4.2.
Accepted a small fix from Eric Larson (https://github.com/larsoner) affecting
`isgeneratorfunction` for old Python versions.
Moved the documentation from ReadTheDocs to GitHub to simplify the
release process and replaced ReStructuredText with Markdown: it is
an inferior solution, but it works better with GitHub and it is good enough.

4.3.2

Accepted a patch from Sylvain Marie (https://github.com/smarie): now the
decorator module can decorate generator functions by preserving their
being generator functions. Set `python_requires='>=2.6, !=3.0.*, !=3.1.*'`
in setup.py, as suggested by https://github.com/hugovk.

4.3.1

Added a section "For the impatient" to the README, addressing an issue
raised by Amir Malekpour. Added support for Python 3.7. Now 
the path to the decorator module appears in the tracebacks, as suggested
by an user at EuroPython 2018.

4.3.0

Extended the decorator family facility to work with positional
arguments and updated the documentation. Removed
`decorator.getargspec` and provided `decorator.getfullargspec`
instead.  This is convenient for users of Python 2.6/2.7, the others
can just use `inspect.getfullargspec`.

Links

• PyPI: https://pypi.org/project/decorator
• Changelog: https://pyup.io/changelogs/decorator/
• Repo: https://github.com/micheles/decorator