travis: require Go 1.13

At this point I'm writing Go 1.13 and indeed we've seen that the code does not compile when using Go 1.13.
m-lab · Feb 11, 2020 · 100604f · 100604f
1 parent 129f902
commit 100604f
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/.travis.yml b/.travis.yml
@@ -1,6 +1,6 @@
 language: go
 go:
-- 1.12.x
+- 1.13.x
 dist: xenial
 
 before_script: