tests: mock date to match snapshot

Author: debater-coder

apps/client/src/consumers/sbhsApi/__snapshots__/useDtt.test.ts.snap

@@ -189,4 +189,4 @@ exports[`the schema > parses a day timetable with no periods 1`] = `
     },
   ],
 }
-`;
+`;

apps/client/src/consumers/sbhsApi/useDtt.test.ts

@@ -1,5 +1,5 @@
 import { dttSchema } from "./schemas";
-import { describe, expect, test } from "vitest";
+import { describe, expect, test, vi } from "vitest";
 
 describe("the schema", () => {
   test("parses a day timetable with no periods", () => {
@@ -119,6 +119,8 @@ describe("the schema", () => {
       shouldDisplayVariations: true,
     };
 
+    vi.setSystemTime(new Date("2023-09-20T08:00:00.000Z"));
+
     expect(dttSchema.parse(dtt)).toMatchSnapshot();
   });
 });