python37Packages.cryptography: 2.6.1 -> 2.7

Changelog:
https://cryptography.io/en/latest/changelog/#v2-7

Important changes:
- BACKWARDS INCOMPATIBLE: We no longer distribute 32-bit manylinux1
  wheels. Continuing to produce them was a maintenance burden.
- BACKWARDS INCOMPATIBLE: Removed the
  cryptography.hazmat.primitives.mac.MACContext interface.
  The CMAC and HMAC APIs have not changed, but they are no longer
  registered as MACContext instances.

pkgs/development/python-modules/cryptography/vectors.nix

@@ -7,7 +7,7 @@ buildPythonPackage rec {
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "1bsqcv3h49dzqnyn29ijq8r7k1ra8ikl1y9qcpcns9nbvhaq3wq3";
+    sha256 = "1g38zw90510azyfrj6mxbslx2gp9yrnv5dac0w2819k9ssdznbgi";
   };
 
   # No tests included