chore: try delay for changelog cache test (#2608)

test/workers/pr/changelog/index.spec.js

+const delay = require('delay');
+
 jest.mock('../../../../lib/platform/github/gh-got-wrapper');
 jest.mock('../../../../lib/datasource/npm');
 jest.mock('got');
@@ -200,7 +202,7 @@ describe('workers/pr/changelog', () => {
           repositoryUrl: 'https://github-enterprise.example.com/chalk/chalk',
         })
       ).toMatchSnapshot();
-
+      await delay(200);
       expect(
         await getChangeLogJSON({
           ...upgrade,