Add torchvision (required by WAN repo)

requirements.txt

@@ -15,6 +15,7 @@ huggingface_hub>=0.24,<1.0
 # Inherited from speed/requirements.txt — repeated here so the Space build
 # resolves all deps in a single pass.
 torch>=2.1
+torchvision>=0.16
 numpy>=1.23
 scipy>=1.10
 PyWavelets>=1.4