updated crypto version max to 51

Author: 4gust

setup.cfg

@@ -53,7 +53,7 @@ install_requires =
     # And we will use the cryptography (X+3).0.0 as the upper bound,
     # based on their latest deprecation policy
     # https://cryptography.io/en/latest/api-stability/#deprecation
-    cryptography>=2.5,<50
+    cryptography>=2.5,<51
 
 
 [options.extras_require]