upgrade all Cargo.toml files to edition=2021

The MSRV is already 1.60, so this doesn't affect much. The only impact
to other code is that we no longer need to explicitly import TryInto.

Cargo.toml

@@ -7,7 +7,7 @@ repository = "https://github.com/BLAKE3-team/BLAKE3"
 license = "CC0-1.0 OR Apache-2.0"
 documentation = "https://docs.rs/blake3"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [features]
 default = ["std"]

b3sum/Cargo.toml

@@ -6,7 +6,7 @@ description = "a command line implementation of the BLAKE3 hash function"
 repository = "https://github.com/BLAKE3-team/BLAKE3"
 license = "CC0-1.0 OR Apache-2.0"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [features]
 neon = ["blake3/neon"]

b3sum/src/main.rs

@@ -1,7 +1,6 @@
 use anyhow::{bail, ensure, Result};
 use clap::Parser;
 use std::cmp;
-use std::convert::TryInto;
 use std::fs::File;
 use std::io;
 use std::io::prelude::*;

c/blake3_c_rust_bindings/Cargo.toml

@@ -7,7 +7,7 @@
 name = "blake3_c_rust_bindings"
 version = "0.0.0"
 description = "TESTING ONLY Rust bindings for the BLAKE3 C implementation"
-edition = "2018"
+edition = "2021"
 
 [features]
 # By default the x86-64 build uses assembly implementations. This feature makes

reference_impl/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "reference_impl"
 version = "0.0.0"
-edition = "2018"
+edition = "2021"
 
 [lib]
 name = "reference_impl"

reference_impl/reference_impl.rs

@@ -18,7 +18,6 @@
 //! ```
 
 use core::cmp::min;
-use core::convert::TryInto;
 
 const OUT_LEN: usize = 32;
 const KEY_LEN: usize = 32;

test_vectors/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "test_vectors"
 version = "0.0.0"
-edition = "2018"
+edition = "2021"
 
 [features]
 neon = ["blake3/neon"]

test_vectors/src/lib.rs

@@ -142,7 +142,6 @@ pub fn parse_test_cases() -> Cases {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::convert::TryInto;
 
     fn test_reference_impl_all_at_once(
         key: &[u8; blake3::KEY_LEN],

tools/compiler_version/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "compiler_version"
 version = "0.0.0"
-edition = "2018"
+edition = "2021"
 
 [build-dependencies]
 cc = "1.0.50"

tools/instruction_set_support/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "instruction_set_support"
 version = "0.0.0"
-edition = "2018"
+edition = "2021"
 
 [dependencies]