Update submodule pointer for repos/builtin 2026/08/19

[AlexanderHrabski-NOAA]

Description

Updates the spack-packages submodule pointer to include recent fms package updates. As of submitting this, the "additional tests" are building.

Dependencies

None.

Issues addressed

Resolves #2079

Applications affected

Only custom envs should be effected -- the required fms version hasn't changed, and any application that builds wasn't affected by the bugs these changes address.

Systems affected

All systems are affected as described above.

Testing

• CI: Note whether the automatic tests (GitHub actions tests that run automatically for every commit) pass or not
  • GitHub actions CI tests pass
  • GitHub actions CI tests do not pass (provide explanation)
  • GitHub actions CI tests skipped (provide explanation if necessary)
• New tests added: List and describe any new tests added to GitHub actions
  • ...
• Additional testing: Add information on any additional tests conducted
  • built the unified-env on my Ubuntu WSL with the oneAPI compilers
  • confirmed the MRE in Missing libyaml symbols when compiling with fms@2025.03+yaml #2079 doesn't produce an error

Checklist

• This PR addresses one issue/problem/enhancement or has a very good reason for not doing so.
• These changes have been tested on the affected systems and applications.
• All dependency PRs/issues have been resolved and this PR can be merged.
• All necessary updates to the documentation (spack-stack wiki) will be made when this PR is merged