fix: add shutdown function for localfs provider (#2781)

# What does this PR do?
this was causing an unnessessary logger warning

## Test Plan
Run `LLAMA_STACK_DIR=. ENABLE_OLLAMA=ollama
OLLAMA_INFERENCE_MODEL=llama3.2:3b llama stack build --template starter
--image-type venv --run` and then `Crtl-C` to shutdown

Signed-off-by: Nathan Weinberg <nweinber@redhat.com>

llama_stack/providers/inline/files/localfs/files.py

@@ -51,6 +51,9 @@ class LocalfsFilesImpl(Files):
             },
         )
 
+    async def shutdown(self) -> None:
+        pass
+
     def _generate_file_id(self) -> str:
         """Generate a unique file ID for OpenAI API."""
         return f"file-{uuid.uuid4().hex}"