custom:
    # PayPal donation button is superior to a paypal.me link because it
    # additionally:
    #   - accepts credit cards without a need to create a PayPal account
    #   - allows monthly subscriptions (requires a PayPal account)
    # However, the URL is rather lengthy and GitHub shows it in full in the
    # Sponsor modal popup.
  - https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=9HJHAH5UDL3GL