chore(deps): bump kotlin_version from 1.8.22 to 1.9.0 in /tutorials/kotlin/Polygons (#1287)

chore(deps): bump kotlin_version in /tutorials/kotlin/Polygons

Bumps `kotlin_version` from 1.8.22 to 1.9.0.

Updates `org.jetbrains.kotlin:kotlin-gradle-plugin` from 1.8.22 to 1.9.0
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](https://github.com/JetBrains/kotlin/compare/v1.8.22...v1.9.0)

Updates `org.jetbrains.kotlin:kotlin-stdlib-jdk7` from 1.8.22 to 1.9.0
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](https://github.com/JetBrains/kotlin/compare/v1.8.22...v1.9.0)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-gradle-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib-jdk7
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

tutorials/kotlin/Polygons/build.gradle

@@ -1,7 +1,7 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 
 buildscript {
-    ext.kotlin_version = '1.8.22'
+    ext.kotlin_version = '1.9.0'
     repositories {
         mavenCentral()
         google()