Update github actions and rtd dependencies

[CamStan]

Description

• update to use actions/checkout v4
• switch to ubuntu-latest (24.04)
• change to available gcc versions (removed gcc 7 and 8)
  • originally added 12 and 13 but this causes a bug to show up
• change spack install action (old one was using an action that is no longer supported)
  • user spack shell support
• update spack packages versions
• change doc dependency versions
• fix compile issue with redefinition of asprintf
• comment out tests producing use-after-free warning
• set lstat() test as expected to fail (undo when lstat is supported)

Motivation and Context

Get GitHub actions running again

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Testing (addition of new tests or update to current tests)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the UnifyFS code style requirements.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• All commit messages are properly formatted.

[CamStan]

The builds seem to being taking a long time to start and hopefully won't time out. I believe this is being cause by a limit that is placed on how many can be running at once for any given account. They were instant in my repo, but I imagine the LLNL account has a long queue.