feat(backends): add faster-qwen3-tts (#8664)

* feat(backends): add faster-qwen3-tts

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* fix: this backend is CUDA only

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* fix: add requirements-install.txt with setuptools for build isolation

The faster-qwen3-tts backend requires setuptools to build packages
like sox that have setuptools as a build dependency. This ensures
the build completes successfully in CI.

Signed-off-by: LocalAI Bot <localai-bot@users.noreply.github.com>

---------

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Signed-off-by: LocalAI Bot <localai-bot@users.noreply.github.com>
Co-authored-by: Ettore Di Giacinto <mudler@localai.io>