add golang 1.12

tagomoris · tagomoris · commit 269339a4b753 · 2019-08-14T14:06:33.000+09:00
Signed-off-by: TAGOMORI Satoshi &lt;tagomoris@gmail.com&gt;
diff --git a/.travis.yml b/.travis.yml
@@ -3,6 +3,7 @@ go:
   - 1.8
   - 1.9
   - 1.11
+  - 1.12
   - tip
 install:
   - go get github.com/bmizerany/assert
