Bump kotlin_version from 1.5.21 to 1.5.30 (#91)

Bumps `kotlin_version` from 1.5.21 to 1.5.30.

Updates `kotlin-gradle-plugin` from 1.5.21 to 1.5.30
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v1.5.30/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.5.21...v1.5.30)

Updates `kotlin-stdlib` from 1.5.21 to 1.5.30
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v1.5.30/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.5.21...v1.5.30)

Updates `kotlin-test-junit` from 1.5.21 to 1.5.30
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v1.5.30/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.5.21...v1.5.30)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-gradle-plugin
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-test-junit
  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>

Author: dependabot[bot]

build.gradle

@@ -1,7 +1,7 @@
 version '1.0-SNAPSHOT'
 
 buildscript {
-    ext.kotlin_version = '1.5.21'
+    ext.kotlin_version = '1.5.30'
     ext.dokka_version = '1.5.0'
     ext.bnd_version = '5.3.0'
     ext.license_version = '0.15.0'