channels: fix YAML indentation

Due to the new anchor added in 3c55dc09 for v2024, the indentation was wrong. Because of this wrong indentation, the source field for v2025dev* is filled with bullseye values instead of bookworm. This completely confuses the dashboard which compares Apertis bullseye-based releases to the bookworm-bases releases.

Signed-off-by: Dylan Aïssi dylan.aissi@collabora.com