Update Kotlin badge version in README.md (#1267)

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## Motivation and Context
Update Kotlin badge version in README.md to 2.2

## Breaking Changes
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#### Type of the changes
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [x] Documentation update
- [ ] Tests improvement
- [ ] Refactoring

#### Checklist
- [x] The pull request has a description of the proposed change
- [x] I read the [Contributing
Guidelines](https://github.com/JetBrains/koog/blob/main/CONTRIBUTING.md)
before opening the pull request
- [x] The pull request uses **`develop`** as the base branch
- [x] Tests for the changes have been added
- [x] All new and existing tests passed

##### Additional steps for pull requests adding a new feature
- [ ] An issue describing the proposed change exists
- [ ] The pull request includes a link to the issue
- [ ] The change was discussed and approved in the issue
- [ ] Docs have been added / updated

Author: lopesc

README.md

@@ -3,7 +3,7 @@
 [![Kotlin Alpha](https://kotl.in/badges/alpha.svg)](https://kotlinlang.org/docs/components-stability.html)
 [![Maven Central](https://img.shields.io/maven-central/v/ai.koog/koog-agents)](https://search.maven.org/artifact/ai.koog/koog-agents)
 [![JetBrains incubator project](https://jb.gg/badges/incubator.svg)](https://github.com/JetBrains#jetbrains-on-github)
-[![Kotlin](https://img.shields.io/badge/kotlin-2.1-blue.svg?logo=kotlin)](http://kotlinlang.org)
+[![Kotlin](https://img.shields.io/badge/kotlin-2.2-blue.svg?logo=kotlin)](http://kotlinlang.org)
 [![CI status](https://img.shields.io/github/checks-status/JetBrains/koog/main)](https://github.com/JetBrains/koog/actions?query=branch%3Amain)
 [![GitHub license](https://img.shields.io/github/license/JetBrains/koog)](LICENSE.txt)