Fixed EncodingWarning in ReferralBanner.
Cleaned up banner (#2, #3).
Add jaraco.tidelift Sphinx extension, implementing
the referral banner through a simple directive:
tidelift-referral-banner.
Refreshed package metadata.
Allow loading token from keyring to support packages that cannot be installed from CI, such as those in Jazzband.
Release notes publishing now accepts a template for the URL for the release notes.
Initial release with 'publish-release-notes' script.