fix: update Octokit import in test file

Replaced `@octokit/core` with `@octokit/rest` in rewards.test.ts.

tests/rewards.test.ts

@@ -2,7 +2,7 @@
 
 import { afterAll, afterEach, beforeAll, beforeEach, describe, it, jest } from "@jest/globals";
 import { drop } from "@mswjs/data";
-import { Octokit } from "@octokit/core";
+import { Octokit } from "@octokit/rest";
 import { Logs } from "@ubiquity-os/ubiquity-os-logger";
 import fs from "fs";
 import { http, passthrough } from "msw";