Remove out of date instructions from `contributing.md`

[dagardner-nv]

Description

• jq and bc are installed in the container by default
• pip intall is no longer needed as this is now executed by cmake

By Submitting this PR I confirm:

• I am familiar with the Contributing Guidelines.
• When the PR is ready for review, new or existing tests cover these changes.
• When the PR is ready for review, the documentation is up to date with these changes.

[dagardner-nv]

/merge