update gpt-neox image to gpt-neox v2.0 and combine with gpt-neox build

[liamcli]

Description

Making a few changes to how we build the deepspeed image for GPT-NeoX.

• We previously had a separate Dockerfile to install gpt-neox into the gpt-neox deepspeed image built here. This is now combined into one script within install_deepspeed.sh that will do further installation for gpt-neox if the deepspeed git passed is the Eleuther AI fork.
• Updating to GPT-NeoX v2 when previously we were on v1

Checklist

• [x] Bump VERSION to make the pushed images are tagged with the right version.
• [x] Licenses should be included for new code which was copied and/or modified from any external code.

[liamcli]

Two flows to build deepspeed and gpt-neox images succeeded in circleci: https://app.circleci.com/pipelines/github/determined-ai/environments?branch=gpt-neox2