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

requirements.txt

@@ -22,7 +22,7 @@ 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
 docutils==0.14            # via botocore

setup.py

@@ -60,7 +60,7 @@ def get_git_sha():
         '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',