Bump bytemuck from 1.20.0 to 1.21.0 (Qiskit#13598)

Bumps [bytemuck](https://github.com/Lokathor/bytemuck) from 1.20.0 to 1.21.0.
- [Changelog](https://github.com/Lokathor/bytemuck/blob/main/changelog.md)
- [Commits](Lokathor/bytemuck@v1.20.0...v1.21.0)

---
updated-dependencies:
- dependency-name: bytemuck
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Cargo.lock

@@ -14,7 +14,7 @@ license = "Apache-2.0"
 #
 # Each crate can add on specific features freely as it inherits.
 [workspace.dependencies]
-bytemuck = "1.20"
+bytemuck = "1.21"
 indexmap.version = "2.7.0"
 hashbrown.version = "0.14.5"
 num-bigint = "0.4"