Push the dockerfile golang version to 1.11

Author: requilence

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.9 AS builder
+FROM golang:1.11 AS builder
 
 RUN curl -fsSL -o /usr/local/bin/dep https://github.com/golang/dep/releases/download/v0.3.2/dep-linux-amd64 && chmod +x /usr/local/bin/dep
 ENV PKG github.com/integram-org/webhook
@@ -19,4 +19,4 @@ RUN apk --no-cache add ca-certificates && rm -rf /var/cache/apk/*
 WORKDIR /app
 
 COPY --from=builder /go/app .
-CMD ["./app"]
+CMD ["./app"]