fix: time formatting for deb changelog

[mudge]

The format string used when formatting changelogs for debs accidentally implied a 12-hour clock (e.g. 15:00 would produce 03:00) when it should be a 24-hour clock.

This is evidenced by the time in the test data incorrectly being 11:05 (11 am) when it should be 23:05 (11 pm).