Bump kotlin_version from 1.7.21 to 1.8.0

Bumps `kotlin_version` from 1.7.21 to 1.8.0.

Updates `kotlin-test-junit5` from 1.7.21 to 1.8.0
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.7.21...v1.8.0)

Updates `kotlin-maven-plugin` from 1.7.21 to 1.8.0

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-test-junit5
  dependency-type: direct:development
  update-type: version-update:semver-minor
- dependency-name: org.jetbrains.kotlin:kotlin-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

pom.xml

@@ -11,7 +11,7 @@
     <properties>
         <ktor_version>2.2.1</ktor_version>
         <kotlin.code.style>official</kotlin.code.style>
-        <kotlin_version>1.7.21</kotlin_version>
+        <kotlin_version>1.8.0</kotlin_version>
         <kotlin.compiler.jvmTarget>11</kotlin.compiler.jvmTarget>
         <logback_version>1.4.5</logback_version>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>