Get Long-Lived Access Token
Use the `GET` /access_token [endpoint](https://developers.facebook.com/docs/threads/get-started/long-lived-tokens#get-a-long-lived-token) to exchange a short-lived Threads user access token for a long-lived token.
Use the `GET` /access_token [endpoint](https://developers.facebook.com/docs/threads/get-started/long-lived-tokens#get-a-long-lived-token) to exchange a short-lived Threads user access token for a long-lived token.