Release v2.9.1 (#758)

## 2.9.1 2023-05-11

### Changes

- Removed unused state variable `bridge_prover_id` by @birchmd. (#749)
- `modexp` has been improved to be greatly faster than before by
@birchmd. (#757)

### Fixes

- Fixed an issue where the owner could call `new` multiple times by
@lempire123. (#733)
- Fixed an issue with `deploy_upgrade` where the upgrade index isn't
cleared by @lempire123. (#741)

---------

Co-authored-by: lempire123 <61431140+lempire123@users.noreply.github.com>
Co-authored-by: Oleksandr Anyshchenko <oleksandr.anyshchenko@aurora.dev>
Co-authored-by: Michael Birch <michael.birch@aurora.dev>

CHANGES.md

@@ -7,6 +7,23 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [2.9.1] 2023-05-11
+
+### Changes
+
+- Removed unused state variable `bridge_prover_id` by [@birchmd]. ([#749])
+- `modexp` has been improved to be greatly faster than before by [@birchmd]. ([#757])
+
+### Fixes
+
+- Fixed an issue where the owner could call `new` multiple times by [@lempire123]. ([#733])
+- Fixed an issue with `deploy_upgrade` where the upgrade index isn't cleared by [@lempire123]. ([#741])
+
+[#749]: https://github.com/aurora-is-near/aurora-engine/pull/749
+[#757]: https://github.com/aurora-is-near/aurora-engine/pull/757
+[#733]: https://github.com/aurora-is-near/aurora-engine/pull/733
+[#741]: https://github.com/aurora-is-near/aurora-engine/pull/741
+
 ## [2.9.0] 2023-04-05
 
 ### Added
@@ -396,7 +413,8 @@ struct SubmitResult {
 
 ## [1.0.0] - 2021-05-12
 
-[Unreleased]: https://github.com/aurora-is-near/aurora-engine/compare/2.9.0...develop
+[Unreleased]: https://github.com/aurora-is-near/aurora-engine/compare/2.9.1...develop
+[2.9.1]: https://github.com/aurora-is-near/aurora-engine/compare/2.9.0...2.9.1
 [2.9.0]: https://github.com/aurora-is-near/aurora-engine/compare/2.8.0...2.9.0 
 [2.8.0]: https://github.com/aurora-is-near/aurora-engine/compare/2.7.0...2.8.0
 [2.7.0]: https://github.com/aurora-is-near/aurora-engine/compare/2.6.1...2.7.0