Update pytest to 3.0.2

[pyup-bot]

There's a new version of pytest available.
You are currently using 3.0.1. I have updated it to 3.0.2

Changelog

3.0.2.dev

• Improve error message when passing non-string ids to pytest.mark.parametrize (1857).
  Thanks okken for the report and nicoddemus_ for the PR.
• Add buffer attribute to stdin stub class pytest.capture.DontReadFromInput
  Thanks joguSD_ for the PR.
• Fix UnicodeEncodeError when string comparison with unicode has failed. (1864)
  Thanks AiOO for the PR.
• pytest_plugins is now handled correctly if defined as a string (as opposed as
  a sequence of strings) when modules are considered for assertion rewriting.
  Due to this bug, much more modules were being rewritten than necessary
  if a test suite uses pytest_plugins to load internal plugins (1888).
  Thanks jaraco for the report and nicoddemus_ for the PR (1891_).
• Do not call tearDown and cleanups when running tests from
  unittest.TestCase subclasses with --pdb
  enabled. This allows proper post mortem debugging for all applications
  which have significant logic in their tearDown machinery (1890). Thanks
  mbyt for the PR.

.. _joguSD: https://github.com/joguSD
.. _AiOO: https://github.com/AiOO
.. _mbyt: https://github.com/mbyt

.. _1857: pytest-dev/pytest#1857
.. _1864: pytest-dev/pytest#1864
.. _1888: pytest-dev/pytest#1888
.. _1891: pytest-dev/pytest#1891
.. _1890: pytest-dev/pytest#1890

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

Happy merging! 🤖