test(client-s3): fix unit test (#1638)

Because the issue with our CI/CD script, the unit doesn't fail even the unit test fails. We will fix it shortly later. 
This change fixes a failed unit test.

Author: AllanZhengYP

clients/client-s3/S3.spec.ts

@@ -87,8 +87,9 @@ describe("Accesspoint ARN", async () => {
       Body: "body",
     });
     expect(result.request.hostname).to.eql(`abc-111-${AccountId}.${OutpostId}.s3-outposts.us-west-2.amazonaws.com`);
+    const date = new Date().toISOString().substr(0, 10).replace(/-/g, ""); //20201029
     expect(result.request.headers["authorization"]).contains(
-      `Credential=${credentials.accessKeyId}/20200928/${region}/s3-outposts/aws4_request`
+      `Credential=${credentials.accessKeyId}/${date}/${region}/s3-outposts/aws4_request`
     );
   });
 });