While deploying #1152, I looked at the footer, which now says
Version 3.9; ICU version: 76.1; Unicode/Emoji version: 16.0.0; Unicodeβ version: 17.0.0; • source
That Version 3.9 is hardcoded, and has been stuck at 3.9 for seven years, since 1c6fa74 (previously it was 3.8).
It might be useful to put the git commit in there instead.