ember-polyfills.deprecate-assign deprication in Ember 4.4

[usamahamed]

I am currently upgrading Ember version to 4.4 and now i get this depreciation with id ember-polyfills.deprecate-assign

Seems it comes from ember-fetch/addon/utils/mung-options-for-fetch.ts

More info: https://deprecations.emberjs.com/v4.x/

versions
ember-simple-auth: 4.2.2
ember-source and ember-cli: 4.4.0
npm: 16.14.0
node: 8.3.1