Cleanup and updates

[Muscraft]

This PR:

• Removes unneeded badges from Cargo.toml and README.md
• Moves to Edition 2021
• Sets MSRV to 1.70.0 to match CI
• Sorted the dependencies alphabetically
• Fully specified dependency versions
• Updated criterion to the newest version

Note: Updating edition and rust-version is "Possibly" a semver-breaking change. It is recommended that this is treated as a minor change, and since this is a pre-1.0.0 crate, we should bump the patch version when this is released, that is 0.9.3.

Note: I could not update toml to the newest version as it stopped supporting borrowing while deserializing, which is needed for the fixture tests.

[zbraniecki]

Note: I could not update toml to the newest version as it stopped supporting borrowing while deserializing, which is needed for the fixture tests.

I hit this too when I was planning to update. From reading the docs they are considering reverting that limitation. But since it's used in tests, we could do allocations if needed. For now I kept us stuck on 0.5