Upgrade to go 1.11 and alpine 3.8

Dockerfile.ci

@@ -1,4 +1,4 @@
-FROM golang:1.9 as builder
+FROM golang:1.11 as builder
 
 RUN mkdir -p /go/src/github.com/stefanprodan/k8s-podinfo/
 
@@ -18,7 +18,7 @@ RUN CGO_ENABLED=0 GOOS=linux go build -ldflags "-s -w \
       -X github.com/stefanprodan/k8s-podinfo/pkg/version.REVISION=${GIT_COMMIT}" \
       -a -installsuffix cgo -o podcli ./cmd/podcli
 
-FROM alpine:3.7
+FROM alpine:3.8
 
 RUN addgroup -S app \
     && adduser -S -g app app \