chatterbox: bump ROCm PyTorch to 2.9.1+rocm6.4 and update index url

Align chatterbox hipblas requirements with ROCm 6.4-compatible wheels.

Author: toalex77

backend/python/chatterbox/requirements-hipblas.txt

@@ -1,6 +1,6 @@
---extra-index-url https://download.pytorch.org/whl/rocm6.0
-torch==2.6.0+rocm6.1
-torchaudio==2.6.0+rocm6.1
+--extra-index-url https://download.pytorch.org/whl/rocm6.4
+torch==2.9.1+rocm6.4
+torchaudio==2.9.1+rocm6.4
 transformers
 numpy>=1.24.0,<1.26.0
 # https://github.com/mudler/LocalAI/pull/6240#issuecomment-3329518289