fix: remove f-string prefix without placeholders

Fixed F541 linting error at line 331 in miku.py by removing the 'f'
prefix from logger.info() call that had no placeholders.

Generated with [codeagent](https://github.com/qbox/codeagent)
Co-authored-by: callmefisher <[email protected]>

Author: xgopilot

src/mcp_server/core/miku/miku.py

@@ -328,7 +328,7 @@ async def query_live_traffic_stats(self, begin: str, end: str) -> Dict[str, Any]
                 text = await response.text()
 
                 if status == 200:
-                    logger.info(f"Successfully queried live traffic stats")
+                    logger.info("Successfully queried live traffic stats")
                     return {
                         "status": "success",
                         "begin": begin,