python-cryptography: bump to version 2.3.1

Version 2.3.1 has been released recently and requested via Github #6967
Fixes #6967.

Also, changed URL to `https://files.pythonhosted.org` ; fewer redirects.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

lang/python/python-cryptography/Makefile

@@ -8,12 +8,12 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=python-cryptography
-PKG_VERSION:=2.2.2
+PKG_VERSION:=2.3.1
 PKG_RELEASE:=1
 
 PKG_SOURCE:=cryptography-$(PKG_VERSION).tar.gz
-PKG_SOURCE_URL:=https://pypi.io/packages/source/c/cryptography
-PKG_HASH:=9fc295bf69130a342e7a19a39d7bbeb15c0bcaabc7382ec33ef3b2b7d18d2f63
+PKG_SOURCE_URL:= https://files.pythonhosted.org/packages/source/c/cryptography
+PKG_HASH:=8d10113ca826a4c29d5b85b2c4e045ffa8bad74fb525ee0eceb1d38d4c70dfd6
 
 PKG_LICENSE:=Apache-2.0 BSD-3-Clause
 PKG_LICENSE_FILES:=LICENSE.APACHE LICENSE.BSD