fix(deps): update dependency immutability-helper to v2.9.1

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change	References
immutability-helper	dependencies	minor	2.8.1 -> 2.9.1	source

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Release Notes

kolodny/immutability-helper

### [`v2.9.1`](https://togithub.com/kolodny/immutability-helper/releases/v2.9.1) [Compare Source](https://togithub.com/kolodny/immutability-helper/compare/v2.9.0...v2.9.1) Revert release to match 2.8.x since upgrading this release is not backwards compatible with typescript v2.x ### [`v2.9.0`](https://togithub.com/kolodny/immutability-helper/releases/v2.9.0) [Compare Source](https://togithub.com/kolodny/immutability-helper/compare/v2.8.1...v2.9.0) #### 2.9.0 ##### Huge thanks to [@​jedmao](https://togithub.com/jedmao) for converting the library to typescript! - **New:** TypeScript definitions are now generated from TypeScript source. meaning they will always be 100% in sync w/ the source code. - **New:** exported `Context` class. - **Deprecated:** stop using `const myUpdate = newContext().update` and start using `const myContext = new Context(); myContext.update(...)`. - **Deprecated:** stop using `update.extend` and start using `import { extend } from 'immutability-helper'` or `const { extend } = new Context()`.

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