Upgrade to pyasn1 0.5.1+ (#375) (#376)

Author: sergey-kurshev

setup.cfg

@@ -35,7 +35,7 @@ packages = find:
 install_requires =
     ecdsa != 0.15
     rsa >=4.0, <5.0, !=4.4, !=4.1.1
-    pyasn1 >=0.4.1, <0.5.0
+    pyasn1 >=0.4.1
 
 [options.extras_require]
 test =