chore: fix type issue

Author: pi0

src/log.ts

@@ -5,7 +5,9 @@ export interface LogOptions {}
 
 const statusColors = { 1: c.blue, 2: c.green, 3: c.yellow } as const;
 
-export const log = (_options: LogOptions = {}): ServerMiddleware => {
+export const log: (options?: LogOptions) => ServerMiddleware = (
+  _options = {},
+) => {
   return async (req, next) => {
     const start = performance.now();
     const res = await next();