deployments/Dockerfile:chore - improve approach to build cli (#853)

Previously we was download the dependencies using `go get`, but since we
are using go modules, a better approach should be use `go mod download`
to download and cache all dependencies.

This commit also add a new build flags on binary to remove debug
information which will make de final binary smaller.

Signed-off-by: Matheus Alcantara <matheus.alcantara@zup.com.br>

deployments/Dockerfile

@@ -19,13 +19,13 @@ RUN apk update && apk add --no-cache git
 ADD . /horusec
 WORKDIR /horusec
 
-RUN go get -t -v -d ./...
+RUN go mod download
 
-RUN env GOOS=linux go build -o /bin/horusec ./cmd/app/main.go
+RUN env GOOS=linux go build -ldflags '-s -w' -o /bin/horusec ./cmd/app/main.go
 
 FROM docker:20.10-git
 
 COPY --from=builder /bin/horusec /usr/local/bin
 RUN chmod +x /usr/local/bin/horusec
 
-CMD [ "sh" ]
+CMD [ "sh" ]