composer update / install is asking for username / password

I am on a debian 9 server and git is asking for username

what should I do?

Package operations: 19 installs, 2 updates, 0 removals
  - Installing drupal/coder (8.3.1):     Authentication required (git.drupal.org):
      Username:
Drupal version: 


Source: https://www.drupal.org/taxonomy/term/21/feed