Remove call to govendor from Travis build

Author: duckpuppy

.travis.yml

@@ -7,12 +7,7 @@ go:
   - "1.14.x"
 
 install:
-# This script is used by the Travis build to install a cookie for
-# go.googlesource.com so rate limits are higher when using `go get` to fetch
-# packages that live there.
-# See: https://github.com/golang/go/issues/12933
-- bash scripts/gogetcookie.sh
-- go get github.com/kardianos/govendor
+  - go mod vendor
 
 script:
 - make test