Bump curve25519-dalek to latest

[salman01zp]

Bump curve25519-dalek to fix nighlty build Issue

dalek-cryptography/curve25519-dalek#619

error[E0658]: use of unstable library feature 'stdsimd'
 --> /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/curve25519-dalek-4.1.2/src/backend/vector/ifma/field.rs:26:5
  |
26 |     _mm256_madd52lo_epu64(z.into(), x.into(), y.into()).into()
  |     ^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #48556 <https://github.com/rust-lang/rust/issues/48556> for more information
  = help: add `#![feature(stdsimd)]` to the crate attributes to enable

error[E0658]: use of unstable library feature 'stdsimd'
 --> /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/curve25519-dalek-4.1.2/src/backend/vector/ifma/field.rs:25:9
  |
25 |     use core::arch::x86_64::_mm256_madd52lo_epu64;
  |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #48556 <https://github.com/rust-lang/rust/issues/48556> for more information
  = help: add `#![feature(stdsimd)]` to the crate attributes to enable

error[E0658]: use of unstable library feature 'stdsimd'
 --> /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/curve25519-dalek-4.1.2/src/backend/vector/ifma/field.rs:34:5
  |
34 |     _mm256_madd52hi_epu64(z.into(), x.into(), y.into()).into()
  |     ^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #48556 <https://github.com/rust-lang/rust/issues/48556> for more information
  = help: add `#![feature(stdsimd)]` to the crate attributes to enable

error[E0658]: use of unstable library feature 'stdsimd'
 --> /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/curve25519-dalek-4.1.2/src/backend/vector/ifma/field.rs:33:9
  |
33 |     use core::arch::x86_64::_mm256_madd52hi_epu64;
  |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #48556 <https://github.com/rust-lang/rust/issues/48556> for more information
  = help: add `#![feature(stdsimd)]` to the crate attributes to enable

error[E0635]: unknown feature `stdarch_x86_avx512`
 --> /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/curve25519-dalek-4.1.2/src/lib.rs:19:13
  |
19 |     feature(stdarch_x86_avx512)
  |             ^^^^^^^^^^^^^^^^^^

[burdges]

I'd still meant to look at this one, but there was enough churn in dalek that I wanted ot be careful.

[salman01zp]

We switched to stable rust to fix this issue. So no rush with updates