Hi mominuzzam,
You need to check that the URL that was using with the callback_url parameter in your oauth/request_token call had been whitelisted in your app settings on apps.twitter.com.
Refer below links.
https://stackoverflow.com/questions/51103139/callback-url-not-approved-by-twitter
https://developer.twitter.com/en/docs/basics/apps/guides/callback-urls