Fix dokka version

gradle/libs.versions.toml

@@ -71,6 +71,7 @@ nordic-scanner = "1.6.0"
 nordic-common = "1.7.1"
 nordic-memfault = "1.0.2"
 nordicPlugins = "1.4.6"
+dokkaPlugin = "1.8.20"
 googleServicesPlugins = "4.3.15"
 firebaseCrashlyticsPlugins = "2.9.2"
 
@@ -220,7 +221,7 @@ android-library = { id = "com.android.library", version.ref = "androidGradlePlug
 android-test = { id = "com.android.test", version.ref = "androidGradlePlugin" }
 ksp = { id = "com.google.devtools.ksp", version.ref = "ksp" }
 hilt = { id = "com.google.dagger.hilt.android", version.ref = "hilt" }
-kotlin-dokka = { id = "org.jetbrains.dokka", version.ref = "kotlin" }
+kotlin-dokka = { id = "org.jetbrains.dokka", version.ref = "dokkaPlugin" }
 kotlin-android = { id = "org.jetbrains.kotlin.android", version.ref = "kotlin" }
 kotlin-jvm = { id = "org.jetbrains.kotlin.jvm", version.ref = "kotlin" }
 kotlin-kapt = { id = "org.jetbrains.kotlin.kapt", version.ref = "kotlin" }