Update pytest to 3.7.0 (#23)

This PR updates [pytest](https://pypi.org/project/pytest) from **3.6.4** to **3.7.0**.



<details>
  <summary>Changelog</summary>
  
  
   ### 3.7.0
   ```
   =========================

Deprecations and Removals
-------------------------

- `2639 &lt;https://github.com/pytest-dev/pytest/issues/2639&gt;`_: ``pytest_namespace`` has been deprecated.

  See the documentation for ``pytest_namespace`` hook for suggestions on how to deal
  with this in plugins which use this functionality.


- `3661 &lt;https://github.com/pytest-dev/pytest/issues/3661&gt;`_: Calling a fixture function directly, as opposed to request them in a test function, now issues a ``RemovedInPytest4Warning``. It will be changed into an error in pytest ``4.0``.

  This is a great source of confusion to new users, which will often call the fixture functions and request them from test functions interchangeably, which breaks the fixture resolution model.



Features
--------

- `2283 &lt;https://github.com/pytest-dev/pytest/issues/2283&gt;`_: New ``package`` fixture scope: fixtures are finalized when the last test of a *package* finishes. This feature is considered **experimental**, so use it sparingly.


- `3576 &lt;https://github.com/pytest-dev/pytest/issues/3576&gt;`_: ``Node.add_marker`` now supports an ``append=True/False`` parameter to determine whether the mark comes last (default) or first.


- `3579 &lt;https://github.com/pytest-dev/pytest/issues/3579&gt;`_: Fixture ``caplog`` now has a ``messages`` property, providing convenient access to the format-interpolated log messages without the extra data provided by the formatter/handler.


- `3610 &lt;https://github.com/pytest-dev/pytest/issues/3610&gt;`_: New ``--trace`` option to enter the debugger at the start of a test.


- `3623 &lt;https://github.com/pytest-dev/pytest/issues/3623&gt;`_: Introduce ``pytester.copy_example`` as helper to do acceptance tests against examples from the project.



Bug Fixes
---------

- `2220 &lt;https://github.com/pytest-dev/pytest/issues/2220&gt;`_: Fix a bug where fixtures overridden by direct parameters (for example parametrization) were being instantiated even if they were not being used by a test.


- `3695 &lt;https://github.com/pytest-dev/pytest/issues/3695&gt;`_: Fix ``ApproxNumpy`` initialisation argument mixup, ``abs`` and ``rel`` tolerances were flipped causing strange comparsion results.
  Add tests to check ``abs`` and ``rel`` tolerances for ``np.array`` and test for expecting ``nan`` with ``np.array()``


- `980 &lt;https://github.com/pytest-dev/pytest/issues/980&gt;`_: Fix truncated locals output in verbose mode.



Improved Documentation
----------------------

- `3295 &lt;https://github.com/pytest-dev/pytest/issues/3295&gt;`_: Correct the usage documentation of ``--last-failed-no-failures`` by adding the missing ``--last-failed`` argument in the presented examples, because they are misleading and lead to think that the missing argument is not needed.



Trivial/Internal Changes
------------------------

- `3519 &lt;https://github.com/pytest-dev/pytest/issues/3519&gt;`_: Now a ``README.md`` file is created in ``.pytest_cache`` to make it clear why the directory exists.
   ```
   
  
</details>


 

<details>
  <summary>Links</summary>
  
  - PyPI: https://pypi.org/project/pytest
  - Changelog: https://pyup.io/changelogs/pytest/
  - Repo: https://github.com/pytest-dev/pytest/issues
  - Homepage: http://pytest.org
</details>

requirements.txt

@@ -2,4 +2,4 @@ flake8==3.5.0
 httplib2==0.11.3
 jsonschema==2.6.0
 markdown-generator==0.1.3
-pytest==3.6.4
+pytest==3.7.0