test: add missing beforeEach import to gh.spec.ts

Import beforeEach from bun:test to fix ReferenceError that occurred
when the test file tried to use beforeEach hooks.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: snomiao

src/gh.spec.ts

@@ -1,4 +1,4 @@
-import { afterAll, describe, expect, it } from "bun:test";
+import { afterAll, beforeEach, describe, expect, it } from "bun:test";
 import { http, HttpResponse } from "msw";
 import { server } from "./test/msw-setup";