Update Dockerfile

Dockerfile

@@ -3,7 +3,8 @@ ARG cudnn_version=7
 FROM nvidia/cuda:${cuda_version}-cudnn${cudnn_version}-devel
 
 RUN apt-get update && apt-get install -y apt-transport-https ca-certificates curl software-properties-common
-RUN curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
+RUN curl -fsSL https://download.docker.com/linux/ubuntu/gpg
+RUN apt-key add -
 RUN apt-get update && add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu bionic test"
 RUN apt-get update && apt-get install -y docker-ce