remove .circleci

.circleci/config.yml

-version: 2
-jobs:
-  build:
-    working_directory: /go/grpc-web-go-client
-    docker:
-      - image: circleci/golang:1.12
-
-    steps:
-      - checkout
-
-      - run:
-          name: build
-          command: CGO_ENABLED=0 go build ./grpcweb
-
-      - run:
-          name: test
-          command: CGO_ENALBED=0 go test -v -race ./grpcweb