fix: Add model parameter to neutts-air gallery definition

The neutts-air model entry was missing the 'model' parameter in its
configuration, which caused LocalAI to fail with an 'Unrecognized model'
error when trying to use it. This change adds the required model parameter
pointing to the HuggingFace repository (neuphonic/neutts-air) so the backend
can properly load the model.

Fixes #8792

Author: localai-bot

gallery/index.yaml

@@ -375,6 +375,8 @@
     - gpu
   overrides:
     backend: neutts
+    parameters:
+      model: neuphonic/neutts-air
     known_usecases:
       - tts
 - name: vllm-omni-z-image-turbo