Update Rust crate bytemuck to v1.21.0 (#22873)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [bytemuck](https://redirect.github.com/Lokathor/bytemuck) |
dependencies | minor | `1.20.0` -> `1.21.0` |

---

### Release Notes

<details>
<summary>Lokathor/bytemuck (bytemuck)</summary>

###
[`v1.21.0`](https://redirect.github.com/Lokathor/bytemuck/compare/v1.20.0...v1.21.0)

[Compare
Source](https://redirect.github.com/Lokathor/bytemuck/compare/v1.20.0...v1.21.0)

</details>

---

### Configuration

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are satisfied.

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rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update
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---

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---

Release Notes:

- N/A

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Cargo.lock

@@ -2005,9 +2005,9 @@ dependencies = [
 
 [[package]]
 name = "bytemuck"
-version = "1.20.0"
+version = "1.21.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8b37c88a63ffd85d15b406896cc343916d7cf57838a847b3a6f2ca5d39a5695a"
+checksum = "ef657dfab802224e671f5818e9a4935f9b1957ed18e58292690cc39e7a4092a3"
 dependencies = [
  "bytemuck_derive",
 ]