frost: incorporate recent fixes; add into_positive_y() to redpallas

[conradoplg]

A bunch of improvements happened in the frost repo that we forgot to incorporate here, mainly some re-exports that were missing; and the RTS re-exports. This PR adds those.

This also adds a into_positive_y() method to KeyPackage and PublicKeyPackage via a trait. This is required in RedPallas by the Zcash specification, which mandates that spend validating keys have positive Y coordinates.

The MSRV test was changed to not use all-features; some FROST code does not follow the MSRV. Since frost is non-default I think this is OK until we address it (or bump MSRV).

And finally, this also changes CI due to a MSRV issue (the latest blake2b_simd MSRV is 1.66, but that should not block us, since users can use lower version of the dependency. And adding a restriction to Cargo.toml seems bad practice. So the workaround is to commit the lockfile.

• Lockfile is now comitted
• CI was changed to update to latest dependencies in the nightly test

Sorry for mixing different things in the same PR. This PR is required by the demo.

[codecov-commenter]

Codecov Report

Merging #68 (1293491) into main (b1bbad7) will decrease coverage by 0.05%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #68      +/-   ##
==========================================
- Coverage   84.77%   84.73%   -0.05%     
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  Files          12       12              
  Lines         762      760       -2     
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- Hits          646      644       -2     
  Misses        116      116              

[natalieesk]

Tests needed to be added but that will be done in a separate issue