python-pip: bump to version 8.1.1

Seems it's some Unicode fix that required a small release.
https://pip.pypa.io/en/stable/news/

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

lang/python-pip/Makefile

@@ -8,12 +8,12 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=python-pip
-PKG_VERSION:=8.1.0
+PKG_VERSION:=8.1.1
 PKG_RELEASE:=1
 
 PKG_SOURCE:=pip-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://pypi.python.org/packages/source/p/pip/
-PKG_MD5SUM:=e9c3844db343f47d16040b32ad9072be
+PKG_MD5SUM:=6b86f11841e89c8241d689956ba99ed7
 
 PKG_BUILD_DIR:=$(BUILD_DIR)/pip-$(PKG_VERSION)
 PKG_USE_MIPS16:=0