Merge pull request elastic#636 from elastic/urllib_1.23

bump max compatible version of urllib3 to <1.23

Author: fxdgear

setup.py

@@ -12,7 +12,7 @@
 f.close()
 
 install_requires = [
- 'urllib3<1.22,>=1.21.1',
+ 'urllib3<1.23,>=1.21.1',
 ]
 tests_require = [
  'requests>=2.0.0, <3.0.0',