Update Rust crate indexmap to v2.9.0 (#28455)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [indexmap](https://redirect.github.com/indexmap-rs/indexmap) |
workspace.dependencies | minor | `2.8.0` -> `2.9.0` |

---

### Release Notes

<details>
<summary>indexmap-rs/indexmap (indexmap)</summary>

###
[`v2.9.0`](https://redirect.github.com/indexmap-rs/indexmap/blob/HEAD/RELEASES.md#290-2025-04-04)

[Compare
Source](https://redirect.github.com/indexmap-rs/indexmap/compare/2.8.0...2.9.0)

- Added a `get_disjoint_mut` method to `IndexMap`, matching Rust 1.86's
    `HashMap` method.
- Added a `get_disjoint_indices_mut` method to `IndexMap` and
`map::Slice`,
    matching Rust 1.86's `get_disjoint_mut` method on slices.
- Deprecated the `borsh` feature in favor of their own `indexmap`
feature,
    solving a cyclic dependency that occured via `borsh-derive`.

</details>

---

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---

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---

Release Notes:

- N/A

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Cargo.lock

@@ -7080,9 +7080,9 @@ dependencies = [
 
 [[package]]
 name = "indexmap"
-version = "2.8.0"
+version = "2.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3954d50fe15b02142bf25d3b8bdadb634ec3948f103d04ffe3031bc8fe9d7058"
+checksum = "cea70ddb795996207ad57735b50c5982d8844f38ba9ee5f1aedcfb708a2aa11e"
 dependencies = [
  "equivalent",
  "hashbrown 0.15.2",