LibJS/Tests: Fix Temporal.PlainDate.prototype.equals() tests

Just calling "expect()" doesn't do anything!

Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainDate/PlainDate.prototype.equals.js

@@ -7,7 +7,7 @@ describe("correct behavior", () => {
         const calendar = { hello: "friends" };
         const firstPlainDate = new Temporal.PlainDate(1, 1, 1, calendar);
         const secondPlainDate = new Temporal.PlainDate(0, 1, 1, calendar);
-        expect(firstPlainDate.equals(firstPlainDate));
-        expect(!firstPlainDate.equals(secondPlainDate));
+        expect(firstPlainDate.equals(firstPlainDate)).toBeTrue();
+        expect(firstPlainDate.equals(secondPlainDate)).toBeFalse();
     });
 });