Update pytest to 3.0.4

[pyup-bot]

There's a new version of pytest available.
You are currently using 3.0.3. I have updated it to 3.0.4

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

Changelog

3.0.4.dev0

==========

• Import errors when collecting test modules now display the full traceback (1976).
  Thanks cwitty for the report and nicoddemus_ for the PR.

• Fix confusing command-line help message for custom options with two or more metavar properties (2004).
  Thanks okulynyak and davehunt_ for the report and nicoddemus_ for the PR.

• When loading plugins, import errors which contain non-ascii messages are now properly handled in Python 2 (1998).
  Thanks nicoddemus for the PR.

• Fixed cyclic reference when pytest.raises is used in context-manager form (1965). Also as a
  result of this fix, sys.exc_info() is left empty in both context-manager and function call usages.
  Previously, sys.exc_info would contain the exception caught by the context manager,
  even when the expected exception occurred.
  Thanks MSeifert04 for the report and the PR.

• Fixed false-positives warnings from assertion rewrite hook for modules that were rewritten but
  were later marked explicitly by pytest.register_assert_rewrite
  or implicitly as a plugin (2005).
  Thanks RonnyPfannschmidt for the report and nicoddemus_ for the PR.

• Report teardown output on test failure (442).
  Thanks matclab or the PR.

• Fix teardown error message in generated xUnit XML.
  Thanks gdyuldin_ or the PR.

• Properly handle exceptions in multiprocessing tasks (1984).
  Thanks adborden for the report and nicoddemus_ for the PR.

• Clean up unittest TestCase objects after tests are complete (1649).
  Thanks d_b_w for the report and PR.

.. _adborden: https://github.com/adborden
.. _cwitty: https://github.com/cwitty
.. _d_b_w: https://github.com/d_b_w
.. _gdyuldin: https://github.com/gdyuldin
.. _matclab: https://github.com/matclab
.. _MSeifert04: https://github.com/MSeifert04
.. _okulynyak: https://github.com/okulynyak

.. _442: pytest-dev/pytest#442
.. _1965: pytest-dev/pytest#1965
.. _1976: pytest-dev/pytest#1976
.. _1984: pytest-dev/pytest#1984
.. _1998: pytest-dev/pytest#1998
.. _2004: pytest-dev/pytest#2004
.. _2005: pytest-dev/pytest#2005
.. _1649: pytest-dev/pytest#1649

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

Happy merging! 🤖