Update pytest to 3.7.4 (#339)

This PR updates [pytest](https://pypi.org/project/pytest) from **3.7.3** to **3.7.4**.



<details>
  <summary>Changelog</summary>
  
  
   ### 3.7.4
   ```
   =========================

Bug Fixes
---------

- `3506 &lt;https://github.com/pytest-dev/pytest/issues/3506&gt;`_: Fix possible infinite recursion when writing ``.pyc`` files.


- `3853 &lt;https://github.com/pytest-dev/pytest/issues/3853&gt;`_: Cache plugin now obeys the ``-q`` flag when ``--last-failed`` and ``--failed-first`` flags are used.


- `3883 &lt;https://github.com/pytest-dev/pytest/issues/3883&gt;`_: Fix bad console output when using ``console_output_style=classic``.


- `3888 &lt;https://github.com/pytest-dev/pytest/issues/3888&gt;`_: Fix macOS specific code using ``capturemanager`` plugin in doctests.



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

- `3902 &lt;https://github.com/pytest-dev/pytest/issues/3902&gt;`_: Fix pytest.org links
   ```
   
  
</details>


 

<details>
  <summary>Links</summary>
  
  - PyPI: https://pypi.org/project/pytest
  - Changelog: https://pyup.io/changelogs/pytest/
  - Homepage: https://docs.pytest.org/en/latest/
</details>

Author: pyup-bot

requirements.txt

@@ -411,9 +411,9 @@ zopfli==0.1.4 \
     --hash=sha256:df7f84a01c0d8c8936e764e63fd0478aa526dc405ee2ad437e633b28cf824141 \
     --hash=sha256:ea204478f5dd4b7c03ec8a25ac5512f5cd85b15e001724289d1676a52c4c1633 \
     --hash=sha256:f5d7840833608f1be3a5f928dbcc0a5ff45ebd8040ea6177864f61a72b773423
-pytest==3.7.3 \
-    --hash=sha256:4abcd98faeea3eb95bd05aa6a7b121d5f89d72e4d36ddb0dcbbfd1ec9f3651d1 \
-    --hash=sha256:2e7c330338b2732ddb992217962e3454aa7290434e75329b1a6739cea41bea6b
+pytest==3.7.4 \
+    --hash=sha256:ad0c7db7b5d4081631e0155f5c61b80ad76ce148551aaafe3a718d65a7508b18 \
+    --hash=sha256:2d7c49e931316cc7d1638a3e5f54f5d7b4e5225972b3c9838f3584788d27f349
 pytest-django==3.4.2 \
     --hash=sha256:2d2e0a618d91c280d463e90bcbea9b4e417609157f611a79685b1c561c4c0836 \
     --hash=sha256:59683def396923b78d7e191a7086a48193f8d5db869ace79acb38f906522bc7b