Update travis for recent go versions.

fluffle · fluffle · commit 5b481cf00ad4 · 2022-03-23T09:38:41.000Z
diff --git a/.travis.yml b/.travis.yml
@@ -2,8 +2,10 @@
 language: go
 
 go:
-  - 1.16.2
-  - 1.15.10
+  - 1.18
+  - 1.17.8
+  - 1.16.15
+  - 1.15.15
 
 sudo : false
 
