travis: Run test on Python 3.4 (msgpack#307)

methane · web-flow · commit d1060de29309 · 2018-07-13T19:54:44.000+09:00
Python 3.4 is not supported officially.
But keep running test for a while, to know when msgpack-python
stop working on Python 3.4 actually.
diff --git a/.travis.yml b/.travis.yml
@@ -4,6 +4,7 @@ cache: pip
 
 python:
   - "2.7"
+  - "3.4"
   - "3.5"
   - "3.6"
   - "3.7-dev"

-Original file line number
+Diff line change
 python:
   - "2.7"
 +  - "3.4"
   - "3.5"
   - "3.6"
   - "3.7-dev"