feat: remove support for special handling of material verification for npm

[laurentsimon]

See #521 (comment)

[ianlewis]

I suppose we may want to be able to verify provenance generated during the public beta. So maybe we can check if it's been generated as of a certain date so that we can check this for provenance generated after the GA?

[laurentsimon]

This should work, good idea.

[asraa]

Or maybe there's a versioning in their buildType or something else to identify stable format?

[ianlewis]

Or maybe there's a versioning in their buildType or something else to identify stable format?

That's maybe an even better idea.

[laurentsimon]

Last time we talk they did not have, ie it was tied to the CLI version. But I think they will change that, so need to follow-up

[ianlewis]

This will get fixed by #641

[ramonpetgrave64]

#641 is merged.