Set a fake date for the details_header_spec

spec/frontend/registry/explorer/components/details_page/details_header_spec.js

 import { shallowMount } from '@vue/test-utils';
 import { GlSprintf } from '@gitlab/ui';
+import { useFakeDate } from 'helpers/fake_date';
 import TitleArea from '~/vue_shared/components/registry/title_area.vue';
 import component from '~/registry/explorer/components/details_page/details_header.vue';
 import { DETAILS_PAGE_TITLE } from '~/registry/explorer/constants';
@@ -15,6 +16,9 @@ describe('Details Header', () => {
     },
   };
 
+  // set the date to Dec 4, 2020
+  useFakeDate(2020, 11, 4);
+
   const findLastUpdatedAndVisibility = () => wrapper.find('[data-testid="updated-and-visibility"]');
 
   const waitForMetadataItems = async () => {