Pin sphinx to 7.3, bump awscli to 2.17, downgrade ipython to 8.17 (#124)

Syncing with the changes at
ICESAT-2HackWeek/website-2024#18 by:

- Pinning `sphinx` explicity to 7.3 (was resolving to 5.1.1 before)
- Upgrade `awscli` from 1.27.76 to 2.17 to resolve conflict on
`docutils` (see
ICESAT-2HackWeek/website-2024#18 (comment))
- Downgrade `ipython` from 8.20.0 to 8.17 to resolve conflict on
`prompt_toolkit` (see
ICESAT-2HackWeek/website-2024#18 (comment))

This PR also adds a 'conda-lock.yml' (following #122) in addition to the
existing 'conda-lock-linux64.yml' file.