Bump the dependencies group in /chat-server with 3 updates (#71)

Bumps the dependencies group in /chat-server with 3 updates: [jvm](https://github.com/JetBrains/kotlin), [plugin.spring](https://github.com/JetBrains/kotlin) and [org.springframework.boot](https://github.com/spring-projects/spring-boot).


Updates `jvm` from 2.2.20 to 2.2.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.2.20...v2.2.21)

Updates `plugin.spring` from 2.2.20 to 2.2.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.2.20...v2.2.21)

Updates `plugin.spring` from 2.2.20 to 2.2.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.2.20...v2.2.21)

Updates `org.springframework.boot` from 3.5.6 to 3.5.7
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v3.5.6...v3.5.7)

---
updated-dependencies:
- dependency-name: jvm
  dependency-version: 2.2.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: dependencies
- dependency-name: plugin.spring
  dependency-version: 2.2.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: dependencies
- dependency-name: plugin.spring
  dependency-version: 2.2.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: dependencies
- dependency-name: org.springframework.boot
  dependency-version: 3.5.7
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: dependencies
...

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

Author: dependabot[bot]

chat-server/build.gradle.kts

@@ -4,10 +4,10 @@ import org.gradle.api.tasks.testing.logging.TestLogEvent.SKIPPED
 import java.util.Properties
 
 plugins {
-    val kotlinVersion = "2.2.20"
+    val kotlinVersion = "2.2.21"
     kotlin("jvm") version kotlinVersion
     kotlin("plugin.spring") version kotlinVersion
-    id("org.springframework.boot") version "3.5.6"
+    id("org.springframework.boot") version "3.5.7"
     id("io.spring.dependency-management") version "1.1.7"
 }