Fix Travis CI failure

.travis.yml

@@ -1,5 +1,6 @@
 # ref: https://docs.travis-ci.com/user/languages/python
 language: python
+dist: trusty
 sudo: true
 services:
   - docker

kubernetes/e2e_test/base.py

@@ -36,6 +36,7 @@ def get_e2e_configuration():
                 urllib3.PoolManager().request('GET', url)
                 config.host = url
                 config.verify_ssl = False
+                urllib3.disable_warnings()
                 break
             except urllib3.exceptions.HTTPError:
                 pass