Fix dockerfile to solve CUDA Linux Repository Key Rotation issue

[pica4500]

Solve CUDA Linux Repsitory Key Rotatino issue

Due to issue, current Dockerfile occurs below error while building.

W: 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
E: The repository 'https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64  InRelease' is not signed.