fix: body not passed in request

[jeroenwienk]

async sync() {
    const params = new URLSearchParams();
    params.append('token', this._token.access_token);
    params.append('sync_token', '*');
    params.append('resource_types', '["user"]');

    // node fetch will set content type to application/x-www-form-urlencoded
    // because of url search params 

    // body is never passed here
    console.log(
      await this.post({
        path: '/sync/v8/sync',
        body: params,
      })
    );

    // this works fine with locally installed node-fetch package
    return fetch('https://api.todoist.com/sync/v8/sync', {
      method: 'POST',
      body: params,
    })
      .then((res) => res.json())
      .then((json) => console.log(json));
  }

[CLAassistant]

All committers have signed the CLA.

[WeeJeWel]

I think it's more clear when opts.body is being set in the } else { of if( json ) {.