Bump org.jetbrains.dokka:dokka-gradle-plugin from 1.8.20 to 1.9.0 (#55)

Bumps [org.jetbrains.dokka:dokka-gradle-plugin](https://github.com/Kotlin/dokka) from 1.8.20 to 1.9.0.
- [Release notes](https://github.com/Kotlin/dokka/releases)
- [Commits](https://github.com/Kotlin/dokka/commits)

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

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

gradle/libs.versions.toml

@@ -2,7 +2,7 @@
 gson = "2.10.1"
 kotlin = "1.9.10"
 kotest = "5.6.2"
-dokka = "1.8.20"
+dokka = "1.9.0"
 nexus-publish-gradle-plugin = "1.3.0"
 # The last version compatible with Java 8 is 0.13.2.
 reckon-gradle-plugin = "0.13.2"