CircleCI: lock CI to go1.11 until GopherJS works with 1.12

Author: johanbrandhorst

.circleci/config.yml

@@ -2,15 +2,15 @@ version: 2
 jobs:
   build:
     docker:
-      - image: "golang:latest"
+      - image: 'golang:1.11'
     working_directory: /go/src/github.com/johanbrandhorst/protobuf
     steps:
       - checkout
       - run: go install ./vendor/github.com/gopherjs/gopherjs
       - run: make build
   dep:
     docker:
-      - image: "golang:latest"
+      - image: 'golang:1.11'
     working_directory: /go/src/github.com/johanbrandhorst/protobuf
     steps:
       - checkout
@@ -19,14 +19,14 @@ jobs:
       - run: git diff --exit-code
   generate:
     docker:
-      - image: "golang:latest"
+      - image: 'golang:1.11'
     working_directory: /go/src/github.com/johanbrandhorst/protobuf
     steps:
       - checkout
       - run:
           name: Install protoc
           environment:
-            PROTOBUF_VERSION: "3.6.1"
+            PROTOBUF_VERSION: '3.6.1'
           command: >
             apt-get update