set retry config defaults without supplying empty object

src/retries.ts

@@ -3,10 +3,10 @@
  */
 export function withRetry<T extends unknown[], U>(
   fn: (...args: T) => Promise<U>,
-  { attempts = 6, backoffMs = (attempt) => 1000 * 2 ** attempt }: {
+  { attempts, backoffMs }: {
     attempts: number;
     backoffMs(attempt: number): number;
-  },
+  } = { attempts: 6, backoffMs: (attempt) => 1000 * 2 ** attempt },
 ): (...args: T) => Promise<U> {
   return async (...args: T) => {
     for (let attempt = 0; attempt < attempts - 1; attempt += 1) {