chore(deps): bump kotlin.version from 1.9.20 to 1.9.21 in /demos (#90)

Bumps `kotlin.version` from 1.9.20 to 1.9.21.

Updates `org.jetbrains.kotlin:kotlin-bom` from 1.9.20 to 1.9.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.9.20...v1.9.21)

Updates `org.jetbrains.kotlin:kotlin-maven-plugin` from 1.9.20 to 1.9.21

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-bom
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

demos/pom.xml

@@ -14,7 +14,7 @@
 		<project.reporting.outputEncoding>${project.build.sourceEncoding}</project.reporting.outputEncoding>
 		<maven.deploy.skip>true</maven.deploy.skip>
 
-		<kotlin.version>1.9.20</kotlin.version>
+		<kotlin.version>1.9.21</kotlin.version>
 		<kotlin.compiler.jvmTarget>${maven.compiler.source}</kotlin.compiler.jvmTarget>
 
 		<!-- overridden by submodule -->