Bug#1141983: New upload: cyrus-imapd 3.12.3 for trixie-backports

Hi!

ftp-masters rejected the original trixie-backports upload, because it 
had been built in trixie, not trixie-backports. This has been fixed.

I also updated this cyrus-imapd package for trixie-backports to 3.12.3.

Reason: 9 CVE's were fixed. See the upstream change log at:

https://www.cyrusimap.org/imap/download/release-notes/3.12/x/3.12.3.html

Packaging changes:

I had to make the following 2 packaging changes compared to what is in 
testing:

1. debhelper-compat lowered from 14 to 13 (14 is not available in Trixie)
2. As a result: I manually restored 
${misc,shlibs,perl}:Depends/Pre-Depends substvars in debian/control. 
Explanation: debhelper-compat 14 does this automatically, hence these 
lines had been removed in testing; the downgrade to 13 required 
restoring these fields.

dget link:

dget 
https://mentors.debian.net/debian/pool/main/c/cyrus-imapd/cyrus-imapd_3.12.3-1~bpo13+1.dsc

Kind regards,
     Edmund