compile error"Vulkan backend does not support quantization at the moment"

[l2002924700]

🐛 Describe the bug

when I compile the pte file from llama-7b-chat as indicated by "https://pytorch.org/executorch/stable/build-run-vulkan.html", I find that the generated ptr file size is too big to run on the edge devices. So I tried to use quantization to the Vulkan bankend. the command is as follows:
python -m examples.models.llama2.export_llama --disable_dynamic_shape --vulkan -kv --use_sdpa_with_kv_cache --checkpoint ~/Llama-2-7b-chat/consolidated.00.pth --params ~/Llama-2-7b-chat/params.json -d fp32 -X -qmode 8da4w --group_size 128 --max_seq_length 1024
then it was generated the error as follows:
Vulkan backend does not support quantization at the moment
I tried to generate the pte file at executor v0.4.0
Conld you help me fix the issue?
Thank you in advanced

Versions

executorvh v0.4.0

[JacobSzwejbka]

@jorgep31415 @SS-JIA