Error while building container

[roclark]

One of Bobber's dependencies, nvidia-imageinary, was updated recently and dropped support for Python 3.6. The base image used by Bobber has Python 3.6 installed by default, causing the container build to fail with an error similar to the following:

 ---> Running in 3911cbaba3e9
Collecting nvidia-pyindex
  Downloading nvidia-pyindex-1.0.9.tar.gz (10 kB)
Building wheels for collected packages: nvidia-pyindex
  Building wheel for nvidia-pyindex (setup.py): started
  Building wheel for nvidia-pyindex (setup.py): finished with status 'done'
  Created wheel for nvidia-pyindex: filename=nvidia_pyindex-1.0.9-py3-none-any.whl size=8399 sha256=5446d1c3fc65066fcdad4f4eb168a337eecbcae38e1956e40f46df5f38cb20a0
  Stored in directory: /root/.cache/pip/wheels/1a/79/65/9cb980b5f481843cd9896e1579abc1c1f608b5f9e60ca90e03
Successfully built nvidia-pyindex
Installing collected packages: nvidia-pyindex
Successfully installed nvidia-pyindex-1.0.9
WARNING: You are using pip version 20.2.4; however, version 21.3.1 is available.
You should consider upgrading via the '/usr/bin/python3 -m pip install --upgrade pip' command.

ERROR: Package 'nvidia-imageinary' requires a different Python: 3.6.9 not in '>=3.7'

WARNING: You are using pip version 20.2.4; however, version 21.3.1 is available.
You should consider upgrading via the '/usr/bin/python3 -m pip install --upgrade pip' command.

The command '/bin/sh -c python3 -m pip install nvidia-pyindex &&     python3 -m pip install         nvidia-imageinary['mxnet']>=1.1.2' returned a non-zero code: 1
nvidia/bobber:6.3.0 build failed. See error above.

The base image needs to be updated with Python 3.7 or newer.