Fix container image for Trixie backport - Use debian:testing instead of debian:12 - This ensures the container matches the target environment (Trixie) - Source is still pulled from sid, but build environment is Trixie

backport-trixie.sh

@@ -65,7 +65,7 @@ run_in_podman() {
         -v /opt:/opt:shared \
         -v "$(pwd):/workspace:Z" \
         -w /workspace \
-        debian:12 \
+        debian:testing \
         bash -c "
             echo '=== Setting up container environment ==='
             apt update -y