travis: install 'ineffassign'

Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>

.travis.yml

@@ -56,6 +56,7 @@ before_install:
  - go get -v -u honnef.co/go/tools/cmd/gosimple
  - go get -v -u honnef.co/go/tools/cmd/unused
  - go get -v -u honnef.co/go/tools/cmd/staticcheck
+ - go get -v -u github.com/gordonklaus/ineffassign
  - ./scripts/install-marker.sh amd64
  - export GOROOT=$(go env GOROOT)