chore: update rust crate indexmap to v2.9.0

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
indexmap	workspace.dependencies	minor	2.6.0 -> 2.9.0

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Release Notes

indexmap-rs/indexmap (indexmap)

v2.9.0

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• 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.

v2.8.0

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• Added indexmap_with_default! and indexset_with_default! to be used with
  alternative hashers, especially when using the crate without std.
• Implemented PartialEq between each Slice and []/arrays.
• Removed the internal rustc-rayon feature and dependency.

v2.7.1

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• Added #[track_caller] to functions that may panic.
• Improved memory reservation for insert_entry.

v2.7.0

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• Added methods Entry::insert_entry and VacantEntry::insert_entry, returning
  an OccupiedEntry after insertion.

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