Bump the cargo group across 2 directories with 1 update

[dependabot]

Updates the requirements on ed25519-dalek to permit the latest version.
Updates ed25519-dalek to 2.1.1

Changelog

Sourced from ed25519-dalek's changelog.

2.1.1

• Update the optional packed-simd dependency to rely on a newer, maintained version of the packed-simd-2 crate.

2.1.0

• Make Scalar::from_bits a const fn, allowing its use in const contexts.

2.0.0

• Fix a data modeling error in the serde feature pointed out by Trevor Perrin which caused points and scalars to be serialized with length fields rather than as fixed-size 32-byte arrays. This is a breaking change, but it fixes compatibility with serde-json and ensures that the serde-bincode encoding matches the conventional encoding for X/Ed25519.
• Update rand_core to 0.5, allowing use with new rand versions.
• Switch from clear_on_drop to zeroize (by Tony Arcieri).
• Require subtle = ^2.2.1 and remove the note advising nightly Rust, which is no longer required as of that version of subtle. See the subtle changelog for more details.
• Update README.md for 2.x series.
• Remove the build.rs hack which loaded the entire crate into its own build.rs to generate constants, and keep the constants in the source code.

The only significant change is the data model change to the serde feature; besides the rand_core version bump, there are no other user-visible changes.

1.x series

1.2.4

• Specify a semver bound for clear_on_drop rather than an exact version, addressing an issue where changes to inline assembly in rustc prevented clear_on_drop from working without an update.

1.2.3

• Fix an issue identified by a Quarkslab audit (and Jack Grigg), where manually constructing unreduced Scalar values, as needed for X/Ed25519, and then performing scalar/scalar arithmetic could compute incorrect results.
• Switch to upstream Rust intrinsics for the IFMA backend now that they exist in Rust and don't need to be defined locally.
• Ensure that the NAF computation works correctly, even for parameters never used elsewhere in the codebase.
• Minor refactoring to EdwardsPoint decompression.
• Fix broken links in documentation.
• Fix compilation on nightly broken due to changes to the #[doc(include)] path root (not quite correctly done in 1.2.2).

... (truncated)

Commits

• 0f07443 Bump curve25519-dalek to 2.1.1.
• bb889e4 Remove deprecated feature flags from .travis.yml.
• d00d4a5 Fix CHANGELOG so that we can note backported patches.
• e6d8afc Add link to Cargo.toml with explanation of packed_simd renaming
• dd71df6 adjusted dependency entry like to pick up latest pick up the latest packed_si...
• 6ffc8dd bumped packed_simd to 0.3.4. resolves #333
• 3fc47ef Bump version to 2.1.0
• f04b830 Merge branch 'master' into develop
• e342f25 Merge pull request #325 from rubdos/const_fn_for_scalar_from_bits
• 3a61a0b Make Scalar::from_bits a const fn.
• Additional commits viewable in compare view

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