Update pyopenssl to 19.0.0 (#517)

This PR updates [pyOpenSSL](https://pypi.org/project/pyOpenSSL) from **18.0.0** to **19.0.0**.



<details>
  <summary>Changelog</summary>
  
  
   ### 19.0.0
   ```
   -------------------


Backward-incompatible changes:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

- ``X509Store.add_cert`` no longer raises an error if you add a duplicate cert.
  `787 &lt;https://github.com/pyca/pyopenssl/pull/787&gt;`_


Deprecations:
^^^^^^^^^^^^^

*none*


Changes:
^^^^^^^^

- pyOpenSSL now works with OpenSSL 1.1.1.
  `805 &lt;https://github.com/pyca/pyopenssl/pull/805&gt;`_
- pyOpenSSL now handles NUL bytes in ``X509Name.get_components()``
  `804 &lt;https://github.com/pyca/pyopenssl/pull/804&gt;`_



----
   ```
   
  
</details>


 

<details>
  <summary>Links</summary>
  
  - PyPI: https://pypi.org/project/pyopenssl
  - Changelog: https://pyup.io/changelogs/pyopenssl/
  - Homepage: https://pyopenssl.org/
  - Docs: https://pythonhosted.org/pyOpenSSL/
</details>

requirements.txt

@@ -145,9 +145,9 @@ pyquery==1.4.0 \
 xmltodict==0.11.0 \
     --hash=sha256:add07d92089ff611badec526912747cf87afd4f9447af6661aca074eeaf32615 \
     --hash=sha256:8f8d7d40aa28d83f4109a7e8aa86e67a4df202d9538be40c0cb1d70da527b0df
-pyOpenSSL==18.0.0 \
-    --hash=sha256:26ff56a6b5ecaf3a2a59f132681e2a80afcc76b4f902f612f518f92c2a1bf854 \
-    --hash=sha256:6488f1423b00f73b7ad5167885312bb0ce410d3312eb212393795b53c8caa580
+pyOpenSSL==19.0.0 \
+    --hash=sha256:c727930ad54b10fc157015014b666f2d8b41f70c0d03e83ab67624fd3dd5d1e6 \
+    --hash=sha256:aeca66338f6de19d1aa46ed634c3b9ae519a64b458f8468aec688e7e3c20f200
 ndg-httpsclient==0.5.1 \
     --hash=sha256:d2c7225f6a1c6cf698af4ebc962da70178a99bcde24ee6d1961c4f3338130d57 \
     --hash=sha256:dd174c11d971b6244a891f7be2b32ca9853d3797a72edb34fa5d7b07d8fff7d4 \