Support mkosi >= 15

[nosada]

ToDo

make (== mkosi build) will succeed in...:

• [x] corespawn
• [ ] buildspawn Removed
• [x] tlspawn
• [x] torspawn
• [x] sngskspawn
• [x] guispawn
• [x] mstdnspawn

using mkosi >= 15

References

• https://github.com/systemd/systemd/tree/main/mkosi.conf.d
• https://github.com/systemd/systemd/tree/main/mkosi.presets
• https://www.freedesktop.org/software/systemd/man/repart.d.html
• https://github.com/systemd/mkosi/blob/main/mkosi/resources/mkosi.md

[nosada]

At least I could build all images using mkosi v19 now