Fix: updated required cryptography version to 2.4.2 to resolve #6509 (#6516)

* Fix: updated required cryptography version to 2.4.2 to resolve #6509

* Fix: updated cryptography version to 2.4.2 to resolve #6509

* Fix: updated cryptography version to 2.4.2 to resolve #6509

* Revert "Fix: updated required cryptography version to 2.4.2 to resolve #6509"

This reverts commit b57b08c8e578d814ac0c6a696afe9ee34ef1e70a.

* Fix: updated cryptography version to 2.4.2

requirements.txt

@@ -20,7 +20,7 @@ click==6.7
 colorama==0.3.9
 contextlib2==0.5.5
 croniter==0.3.25
-cryptography==1.9
+cryptography==2.4.2
 decorator==4.3.0          # via retry
 defusedxml==0.5.0         # via python3-openid
 et-xmlfile==1.0.1         # via openpyxl

setup.py

@@ -58,7 +58,7 @@ setup(
         'click>=6.0, <7.0.0',  # click >=7 forces "-" instead of "_"
         'colorama',
         'contextlib2',
-        'cryptography',
+        'cryptography>=2.4.2',
         'flask>=1.0.0, <2.0.0',
         'flask-appbuilder>=1.12.1, <2.0.0',
         'flask-caching',