Our current CI is using deprecated actions and should be updated

[butlerpd]

Describe the bug
when our CI actions run they generate a bunch of warnings all around the fact that we are using a couple of old versions of github/actions which are using a deprecated node.js version (16 instead of 20).

These actions in question are:
actions/setup-python and actions/checkout which are currently running version 4 and 3 respectively. They should be bumped to version 5 and 4 respectively.

Both ci.yml and nightly-build need to be updated. They should be updated in both the 6.0.0_release branch and the main branch