update dockerfile

Author: kohbis

.dockerignore

@@ -0,0 +1,5 @@
+.git
+.github
+.gitignore
+.goreleaser.yml
+README.md

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.15.2-alpine as builder
+FROM golang:1.15.2-buster as builder
 ENV CGO_ENABLED 0
 ENV GOOS linux
 ENV GOARCH amd64
@@ -7,6 +7,6 @@ WORKDIR /go/src/github.com/kohbis/dimg/
 COPY . .
 RUN go build
 
-FROM alpine:3.11
+FROM alpine:3.12 as runner
 COPY --from=builder /go/src/github.com/kohbis/dimg/dimg /usr/local/bin/dimg
 ENTRYPOINT ["dimg"]