Update edition in .rustfmt.toml and pre-commit hook (#4543)

# Description of Changes

We've updated to 2024
(https://github.com/clockworklabs/SpacetimeDB/pull/3802).

I'm just adding `edition` to `.rustfmt.toml`, and removing the hardcoded
edition from the pre-commit hook. This fixes the pre-commit hook
complaining about us using Rust 2024 features.

# API and ABI breaking changes

None

# Expected complexity level and risk

1

# Testing
- [x] `rustfmt crates/auth/src/identity.rs` now succeeds for me

---------

Co-authored-by: Zeke Foppa <bfops@users.noreply.github.com>

.rustfmt.toml

@@ -1,2 +1,3 @@
 max_width = 120
 style_edition = "2021"
+edition = "2024"

git-hooks/hooks/pre-commit

@@ -77,7 +77,7 @@ if [ -n "$exe" ]; then
             if [[ "$line" == *.rs ]]; then
 		echo "Formatting changed file: ${line:3}..."
                 # format file
-                rustfmt --edition 2021 "$git_repo/${line:3}"	      
+                rustfmt "$git_repo/${line:3}"
                 # add changes
                 git add "$git_repo/${line:3}"
             fi