Bump rayx submodule to fix/ue112-rml-materials (74a489fb)

Pulls in the RML material/energy-distribution fixes from
Atraxus/rayx@fix/ue112-rml-materials, fast-forwarded from hz-b/rayx
master. Purely additive/internal to rayx-core (material tables, RML
parsing, collision handling); no change to the nanobind-exposed API
surface, verified against the src-layout restructuring on this branch.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: Atraxus