Update Docker image to Alpine Linux 3.10.0

Dockerfile

@@ -1,11 +1,11 @@
-FROM golang:1.12-alpine3.9 as build
+FROM golang:1.12-alpine3.10 as build
 ENV GO111MODULE=on
 WORKDIR /go/src/app
 RUN apk add --no-cache --update build-base git
 COPY . .
 RUN make linux-__MINIFLUX_ARCH__ VERSION=__MINIFLUX_VERSION__
 
-FROM __BASEIMAGE_ARCH__/alpine:3.9
+FROM __BASEIMAGE_ARCH__/alpine:3.10.0
 EXPOSE 8080
 ENV LISTEN_ADDR 0.0.0.0:8080
 RUN apk --no-cache add ca-certificates tzdata