Docker file

Dear Author, Thank you very much for your excellent effort!
When I attempted to build the Docker file, I received the following issues. Please help!

ERROR [ 4/29] RUN apt-get update && apt-get install -y --no-install-recommends cuda-cudart-10-1=10.1.243-1 cuda-compat-10-1 && ln -s cuda-10.1 /usr/local/cuda && rm -rf /var/lib/apt/lists/*

GPG error: https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64 InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A4B469963BF863CC

ERROR: failed to solve: process "/bin/sh -c apt-get update && apt-get install -y --no-install-recommends cuda-cudart-$CUDA_PKG_VERSION cuda-compat-10-1 && ln -s cuda-10.1 /usr/local/cuda && rm -rf /var/lib/apt/lists/*" did not complete successfully: exit code: 100

[yeruimin]

update the key before installing packages.

RUN apt-key del 7fa2af80
RUN apt-key adv --fetch-keys https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/3bf863cc.pub
RUN apt-key adv --fetch-keys https://developer.download.nvidia.com/compute/machine-learning/repos/ubuntu1804/x86_64/7fa2af80.pub