fix(ci): use go 1.11.4 to fix git export-subst causes hash mismatches (golang/go#28094)

Author: Ryan-Git

.travis.yml

@@ -1,7 +1,7 @@
 language: go
 
 go:
-  - "1.11"
+  - "1.11.4"
 
 env:
   - GO111MODULE=on
@@ -23,4 +23,4 @@ jobs:
         - docker build -t moiot/gravity-gatekeeper:${TRAVIS_TAG} -f Dockerfile.gatekeeper .
         - echo "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin
         - docker push moiot/gravity-operator:${TRAVIS_TAG}
-        - docker push moiot/gravity-gatekeeper:${TRAVIS_TAG}
+        - docker push moiot/gravity-gatekeeper:${TRAVIS_TAG}n