Bump k256 dependency version from 0.9.6 to 0.13.1

[Arjentix]

I ask for this feature, because currently used version of k256 is pretty outdated and it loads some other oudated crates, which breaks my Iroha 2 build.

Specifically k256 depends on ecdsa which depends on signature. Given that dependency graph current ursa uses signature >=1.3.0, <1.4.0 and when I need to link with another crate which uses another version constraints for signature build fails because it fails to select a proper version. I.e.
I need to link my crate with ursa and with cargo crate. cargo v0.69.1 depends on more updated version of signature with signature >=1.6.2, <1.7 version constraint.

Looks like new version of k256 depends on the new version of ecdsa which depends on signature v2. With that it will be totally okay to have signature v1 and signature v2 in one crate.