d/control: add recommends for new feature dependencies

d/control: add recommends for new feature dependencies

* libdbd-sqlite3-perl is needed for the caching of DecodeShortUrl
* libmail-dmarc-perl [0]  is used for DMARC and Authentication-Results
  handling
* libnet-idn2-perl [1] is needed if utf-8 domain-names are to be
  analyzed (or added to block/welcomelists)

the latter 2 packages are not in bullseye yet, but build and install
cleanly

[0]
https://salsa.debian.org/noahm/libmail-dmarc-perl
[1]
https://salsa.debian.org/perl-team/modules/packages/libnet-libidn2-perl

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>