Update Dockerfile

Dockerfile

@@ -2,7 +2,7 @@ FROM golang:1.14.1
 
 ENV DEBIAN_FRONTEND=noninteractive 
 RUN 	go get -u github.com/golang/dep/cmd/dep  github.com/ugorji/go/codec/codecgen  \
-        && apt-get update && apt-get install -y libgs-dev ghostscript \
+        && apt-get update && apt-get install -y libgs-dev ghostscript npm zlib1g-dev \
 		&& rm -rf /var/lib/apt/lists/* 
 
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