Don't send autoremvoal mails on the first day a package is marked for
autoremoval. If it is still marked for autoremoval after that, the mail will
be sent.

This should avoid sending mail in situations where a package is incorrectly
marked for autoremoval right after something changes. This can happen when a
newer version, which fixes the bug, just migrated to testing.

See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=926455