Mylar3 & Medusa: use trixie non-free for unrar, not bookworm (#16072)

Both scripts provision Debian 13 containers (var_version 13) but add a
Debian 12 (bookworm) non-free apt source to obtain unrar.

Because the base image only enables the `main` component, trixie's
non-free is never enabled, so bookworm is the only source offering
unrar and the containers deterministically install the Debian 12 build
(1:6.2.6-1+deb12u1) instead of trixie's 1:7.1.8-1.

Mylar3 additionally never removes the source, leaving bookworm
non-free and non-free-firmware permanently enabled at priority 500 on
a Debian 13 system.

Aligns both with install/sabnzbd-install.sh, which already sets up the
same unrar dependency correctly against trixie.

Co-authored-by: Tim Moore <tim.moore@ingenuity.com.au>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

install/medusa-install.sh

@@ -20,7 +20,7 @@ $STD apt install -y \
   mediainfo
 
 cat <<EOF >/etc/apt/sources.list.d/non-free.list
-deb https://deb.debian.org/debian bookworm main contrib non-free non-free-firmware
+deb https://deb.debian.org/debian trixie main contrib non-free non-free-firmware
 EOF
 $STD apt update
 $STD apt install -y unrar

install/mylar3-install.sh

@@ -17,8 +17,9 @@ msg_info "Installing Dependencies"
 cat <<EOF >/etc/apt/sources.list.d/non-free.sources
 Types: deb
 URIs: http://deb.debian.org/debian
-Suites: bookworm
+Suites: trixie
 Components: non-free non-free-firmware
+Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg
 EOF
 $STD apt update
 $STD apt install -y unrar