fix(ahrefs-client): drop redundant sinon.restore() in afterEach

In sinon 21.1.x, the static sinon.restore() also uninstalls fake timers
installed via a custom sandbox (sandbox.useFakeTimers). The ahrefs-client
test installs the clock once in `before` and called `sinon.restore()` in
`afterEach`, which uninstalled the clock after the first test under sinon
21.1.x. Subsequent tests got real `new Date()`, breaking 10 tests on
Nock URL matches and fullAuditRef assertions.

The call was unnecessary: this test only uses sandbox.useFakeTimers and
never creates any static-sinon stubs, so it was a no-op in 21.0.3 and
harmful in 21.1.x.

Author: solaris007

packages/spacecat-shared-ahrefs-client/test/index.test.js

@@ -204,7 +204,6 @@ describe('AhrefsAPIClient', () => {
   });
 
   afterEach(() => {
-    sinon.restore();
     nock.cleanAll();
   });