use go1.13

Hideo Hattori · Hideo Hattori · commit 8e05ec68a099 · 2020-02-13T15:09:32.000+09:00
diff --git a/.travis.yml b/.travis.yml
@@ -5,8 +5,7 @@ env:
 
 matrix:
   include:
-    - go: 1.11.x
-      env: DEPLOY_BUILD=true
+    - go: 1.13.x
     - go: tip
 
 install:
