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.