Support multi-arch docker image

Dockerfile

@@ -2,15 +2,15 @@ FROM golang:1.18 AS builder
 
 WORKDIR /go/src/github.com/whywaita/myshoes
 
-ENV CGO_ENABLED=0
-ENV GOOS=linux
-ENV GOARCH=amd64
-
 RUN go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
 RUN go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest
 RUN apt-get update -y \
     && apt-get install -y protobuf-compiler
 
+ENV CGO_ENABLED=0
+ENV GOOS=linux
+ENV GOARCH=amd64
+
 COPY . .
 RUN make build-linux
 
@@ -23,4 +23,4 @@ RUN apk add --no-cache ca-certificates \
 
 COPY --from=builder /go/src/github.com/whywaita/myshoes/myshoes-linux-amd64 /app
 
-CMD ["/app"]
+CMD ["/app"]