Replaced curl with ADD in Dockerfile

Author: carlosadiegosysdig

Dockerfile

@@ -1,9 +1,8 @@
 FROM quay.io/prometheus/golang-builder as builder
 
 ARG PROMU_VERSION=0.13.0
-RUN curl -LJO https://github.com/prometheus/promu/releases/download/v${PROMU_VERSION}/promu-${PROMU_VERSION}.linux-amd64.tar.gz 
-RUN tar -xvzf promu-${PROMU_VERSION}.linux-amd64.tar.gz 
-RUN mv promu-${PROMU_VERSION}.linux-amd64/promu /go/bin
+ADD  https://github.com/prometheus/promu/releases/download/v${PROMU_VERSION}/promu-${PROMU_VERSION}.linux-amd64.tar.gz ./
+RUN tar -xvzf promu-${PROMU_VERSION}.linux-amd64.tar.gz && mv promu-${PROMU_VERSION}.linux-amd64/promu /go/bin
 
 ADD .   /go/src/github.com/prometheus-community/elasticsearch_exporter
 WORKDIR /go/src/github.com/prometheus-community/elasticsearch_exporter