Add open3d to requirements: needed by mvadapter pipeline_texture (Python 3.10 has wheels)

requirements.txt

@@ -29,7 +29,7 @@ xformers
 # 3D / Mesh
 trimesh
 fast-simplification
-# open3d: no Python 3.13 wheels — not used in this Space
+open3d  # needed by mvadapter pipeline_texture.py (Space runs Python 3.10 which has wheels)
 # pymeshlab: no Python 3.13 wheels — not used in this Space
 pygltflib
 # pyrender: no Python 3.13 wheels — not used in this Space