images: adjust to sxmo packaging rename
In edge, the package was split from:
postmarketos-ui-sxmo
into:
postmarketos-ui-sxmo-de-sway
postmarketos-ui-sxmo-de-dwm
Related: https://gitlab.com/postmarketOS/pmaports/-/issues/1302
Merging after CI passes, so the next edge images for sxmo don't fail.