sphinx-fix

1Build: state=Finished  success=False  exit=1  build finished with problems, 1 warning.2 3Findings (1):4  Tier 3 — warnings:5    [T3] py-xref-target-not-found  python/ray/train/collective/__init__.py:docstring of ray.train.collective.broadcast_from_rank_zero:6          msg:    py:exc reference target not found: pickle.PicklingError7          fix:    Check for a co-occurring tier-2 autosummary-stub-not-found or tier-1 import abort for the same module first. If present, fix that root (up to and including reverting an in-progress API-ref restructuring) and rebuild -- the flood clears at once. Only when the build is otherwise healthy is the reference itself wrong: repoint to the correct dotted path, or fix the intersphinx target for a stdlib/third-party name. For a third-party target that DOES exist upstream, suspect a stale committed inventory snapshot: upstream added the symbol after doc/source/_intersphinx/<project>.inv was last refreshed. Fix by running `python doc/source/_intersphinx/refresh.py <project>` and committing the updated .inv, not by editing the reference.8          safety: judgment (needs your call)9 10Unclassified (0) — no rule matched; resolve with the user, then file a skill-improvement ticket to add a rule:11 12Suppressed (0) — known-benign, not actionable:13 14Next: apply the fixes above, then rebuild and re-run to confirm clean.15