Upgrade CI image to Go 1.12 (part 2)

.gitlab/ci/global.gitlab-ci.yml

@@ -202,7 +202,7 @@
     - name: redis:alpine
 
 .use-pg10:
-  image: "registry.gitlab.com/gitlab-org/gitlab-build-images:ruby-2.6.3-golang-1.11-git-2.22-chrome-73.0-node-12.x-yarn-1.16-postgresql-10-graphicsmagick-1.3.33"
+  image: "registry.gitlab.com/gitlab-org/gitlab-build-images:ruby-2.6.3-golang-1.12-git-2.22-chrome-73.0-node-12.x-yarn-1.16-postgresql-10-graphicsmagick-1.3.33"
   services:
     - name: postgres:10.9
       command: ["postgres", "-c", "fsync=off", "-c", "synchronous_commit=off", "-c", "full_page_writes=off"]
@@ -216,7 +216,7 @@
     - name: docker.elastic.co/elasticsearch/elasticsearch:5.6.12
 
 .use-pg10-ee:
-  image: "registry.gitlab.com/gitlab-org/gitlab-build-images:ruby-2.6.3-golang-1.11-git-2.22-chrome-73.0-node-12.x-yarn-1.16-postgresql-10-graphicsmagick-1.3.33"
+  image: "registry.gitlab.com/gitlab-org/gitlab-build-images:ruby-2.6.3-golang-1.12-git-2.22-chrome-73.0-node-12.x-yarn-1.16-postgresql-10-graphicsmagick-1.3.33"
   services:
     - name: postgres:10.9
       command: ["postgres", "-c", "fsync=off", "-c", "synchronous_commit=off", "-c", "full_page_writes=off"]