Bump go version to 1.13

SimonBaeumer · SimonBaeumer · commit fecfb4fccde1 · 2019-10-17T09:40:46.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -10,7 +10,7 @@ stages:
   - deploy
 
 go:
-  - 1.12.x
+  - 1.13.x
 
 sudo: required
 dist: trusty
