The composer.json incorrectly claims that this release is still compatible with Drupal 8.7 and running composer update will try to update that. Either update to Drupal 8.8 or require an earlier version until you can do so:
composer require drupal/token:1.6
Contributors (8)
Chris Burge, Berdir, Matroskeen, Sergiu Stici, thalles, maximpodorov, idebr, czigor
This release is Drupal 9 compatible. There have been minor changes to some automated tests, and some deprecated code has been rewritten, but there are no changes to the functionality.