build: run travis against go 1.13

Roasbeef · Roasbeef · commit 7e5749c21dff · 2019-09-09T03:08:14.000-07:00
diff --git a/.travis.yml b/.travis.yml
@@ -7,7 +7,7 @@ cache:
     - $GOPATH/src/github.com/golang
 
 go:
-  - "1.12.x"
+  - "1.13.x"
 
 sudo: required
 
