migrate PyArray contructors to Bound API (Part 3)

[Icxolu]

Following #418

This finalizes the migration of PyArray constructors to the Bound API. This migrates with PyArray::{from_iter, from_array, from_vec}, alongside with IntoPyArray and ToPyArrray which they use under the hood. I think with this all constructors should be migrated.

[maffoo]

Out of curiosity, is this the last change needed before it would be possible to make a release compatible with pyo3 0.21? Is there any timeline for such a release?

[Icxolu]

There is still 2 or 3 PRs left to migrate everything:

• disable pyo3s gil-ref feature
• convert inner, dot and einsum
• convert pyarray! macro

I can't say anything on a release schedule. Depending on the project you need this for, you could also try using cargo's patch to build against main in the meantime and see if everything works for you.

[adamreichold]

Depending on the project you need this for, you could also try using cargo's patch to build against main in the meantime and see if everything works for you.

I think we are still on the beta version and I am not completely sure whether Cargo will unify this with a dependency on the release version.

[adamreichold]

LGTM except for cosmetics.

Please also bump the dependency to the final version of PyO3 0.21 while fixing those up.