Update pytest to 4.1.1 (#506)

This PR updates [pytest](https://pypi.org/project/pytest) from **4.1.0** to **4.1.1**.



<details>
  <summary>Changelog</summary>
  
  
   ### 4.1.1
   ```
   =========================

Bug Fixes
---------

- `2256 &lt;https://github.com/pytest-dev/pytest/issues/2256&gt;`_: Show full repr with ``assert a==b`` and ``-vv``.


- `3456 &lt;https://github.com/pytest-dev/pytest/issues/3456&gt;`_: Extend Doctest-modules to ignore mock objects.


- `4617 &lt;https://github.com/pytest-dev/pytest/issues/4617&gt;`_: Fixed ``pytest.warns`` bug when context manager is reused (e.g. multiple parametrization).


- `4631 &lt;https://github.com/pytest-dev/pytest/issues/4631&gt;`_: Don&#39;t rewrite assertion when ``__getattr__`` is broken



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

- `3375 &lt;https://github.com/pytest-dev/pytest/issues/3375&gt;`_: Document that using ``setup.cfg`` may crash other tools or cause hard to track down problems because it uses a different parser than ``pytest.ini`` or ``tox.ini`` files.



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

- `4602 &lt;https://github.com/pytest-dev/pytest/issues/4602&gt;`_: Uninstall ``hypothesis`` in regen tox env.
   ```
   
  
</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>

requirements.txt

@@ -423,9 +423,9 @@ zopfli==0.1.6 \
     --hash=sha256:ed2293c11c2685bbd70bad0103285279406a77622e06de794d59c2180fecaa6a
 huey==1.10.5 \
     --hash=sha256:c0ead41821462e111873102075addaa4d7040fbda52db8834c4302207758d5e2
-pytest==4.1.0 \
-    --hash=sha256:3e65a22eb0d4f1bdbc1eacccf4a3198bf8d4049dea5112d70a0c61b00e748d02 \
-    --hash=sha256:5924060b374f62608a078494b909d341720a050b5224ff87e17e12377486a71d
+pytest==4.1.1 \
+    --hash=sha256:41568ea7ecb4a68d7f63837cf65b92ce8d0105e43196ff2b26622995bb3dc4b2 \
+    --hash=sha256:c3c573a29d7c9547fb90217ece8a8843aa0c1328a797e200290dc3d0b4b823be
 pytest-django==3.4.5 \
     --hash=sha256:e88e471d3d0f9acfb6293bb03d0ee8a33ed978734e92ea6b5312163a6c9e87cc \
     --hash=sha256:1a5d33be930e3172fa238643a380414dc369fe8fa4b3c3de25e59ed142950736