[model] fix use_cache patching for gemma3 multimodal (#7500)

Author: ysjprojects

src/llamafactory/model/patcher.py

@@ -107,6 +107,10 @@ def patch_config(
         setattr(config, "use_cache", True)
         logger.info_rank0("Using KV cache for faster generation.")
 
+    if config.architectures[0] == "Gemma3ForConditionalGeneration" and not model_args.use_cache:
+        text_config = config.text_config
+        setattr(text_config, "use_cache", False)
+
     if getattr(config, "model_type", None) == "qwen":
         setattr(config, "use_flash_attn", model_args.flash_attn == "fa2")
         for dtype_name, dtype in [("fp16", torch.float16), ("bf16", torch.bfloat16), ("fp32", torch.float32)]: