ko build does not give me a way to put annotations in a multi-platform manifest

[MikeSpreitzer]

As far as I can tell, there is not way that a ko build user, when building a multi-platform manifest, can specify annotations that go into that manifest. It would be good if there were a way.

[github-actions]

This issue is stale because it has been open for 90 days with no
activity. It will automatically close after 30 more days of
inactivity. Keep fresh with the 'lifecycle/frozen' label.