add gemma 270m for test use

src/utils.py

@@ -35,6 +35,7 @@ sensevoice_models = {
 
 available_gguf_llms = {
     "Gemma-3-1B": ("bartowski/google_gemma-3-1b-it-qat-GGUF", "google_gemma-3-1b-it-qat-Q4_0.gguf"),
+    "Gemma-3-270M": ("bartowski/google_gemma-3-270m-it-qat-GGUF", "google_gemma-3-270m-it-qat-Q8_0.gguf"),
     "Gemma-3-3N-E2B": ("unsloth/gemma-3n-E2B-it-GGUF", "gemma-3n-E2B-it-Q4_0.gguf"),
     "Gemma-3-3N-E4B": ("unsloth/gemma-3n-E4B-it-GGUF", "gemma-3n-E4B-it-Q4_0.gguf"),
 }