OSV-2026-846 Bad-cast to AMFColor from AMFMetadata

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=519360629 Crash type: Bad-cast Crash state: Bad-cast to AMFColor from AMFMetadata Assimp::AMFImporter::SPPMaterial::GetColor Assimp::AMFImporter::PostprocessBuildMeshSet...