feat: Add gemini-3.1-flash-tts-preview model to options

PiperOrigin-RevId: 900285928

Author: Annhiluc

google/genai/_interactions/types/model.py

@@ -38,6 +38,7 @@
         "gemini-3.1-pro-preview",
         "gemini-3.1-flash-image-preview",
         "gemini-3.1-flash-lite-preview",
+        "gemini-3.1-flash-tts-preview",
         "lyria-3-clip-preview",
         "lyria-3-pro-preview",
     ],

google/genai/_interactions/types/model_param.py

@@ -40,6 +40,7 @@
         "gemini-3.1-pro-preview",
         "gemini-3.1-flash-image-preview",
         "gemini-3.1-flash-lite-preview",
+        "gemini-3.1-flash-tts-preview",
         "lyria-3-clip-preview",
         "lyria-3-pro-preview",
     ],