Update .travis.yml

Author: rangsimanketkaew

.travis.yml

@@ -11,7 +11,8 @@ python:
 
 install:
   # - pip install octadist
-  - pip install -i https://test.pypi.org/simple/ octadist
+  # - pip install -i https://test.pypi.org/simple/ octadist
+  - python -m pip install --index-url https://test.pypi.org/simple/ octadist
 
 script:
   - cd example-py