docs(deps): update plugin dokka to v1.8.20

Author: renovate[bot]

gradle/libs.versions.toml

@@ -22,7 +22,7 @@ ktor-serialization = { module = "io.ktor:ktor-serialization-kotlinx-json", versi
 kotlin-testing = ["archunit", "kotest-junit5", "kotest-assertions-core", "kotest-assertions-core-jvm"]
 
 [plugins]
-dokka = { id ="org.jetbrains.dokka", version = "1.8.10" }
+dokka = { id ="org.jetbrains.dokka", version = "1.8.20" }
 kotlin-jvm = { id = "org.jetbrains.kotlin.jvm", version.ref = "kotlin" }
 kotlin-qa = { id = "org.danilopianini.gradle-kotlin-qa", version = "0.43.0" }
 kotlin-serialization = { id = "org.jetbrains.kotlin.plugin.serialization", version.ref = "kotlin" }