package/python-keyring: switch SITE to https

Fixes
http://autobuild.buildroot.net/results/f73/f7322f19303daa3d403f2c0f13379d947431300d/

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/python-keyring/python-keyring.mk

@@ -6,7 +6,7 @@
 
 PYTHON_KEYRING_VERSION = 3.0.5
 PYTHON_KEYRING_SOURCE = keyring-$(PYTHON_KEYRING_VERSION).zip
-PYTHON_KEYRING_SITE = http://pypi.python.org/packages/source/k/keyring
+PYTHON_KEYRING_SITE = https://pypi.python.org/packages/source/k/keyring
 PYTHON_KEYRING_SETUP_TYPE = setuptools
 PYTHON_KEYRING_LICENSE = python software foundation license