Create a GitHub release for 2.28.0

[ryandesign]

The tag for 2.28.0 was created in 2023 but no corresponding GitHub release was created, so the front page of this project still advertises the previous release, 2.25.0 from 2018, as the most recent one. Please create a 2.28.0 release and remember to create releases for all future version tags that you create.