Adjust obtaining the value for `publishPlugin.channels` property.

build.gradle.kts

@@ -126,6 +126,6 @@ tasks {
         // The pluginVersion is based on the SemVer (https://semver.org) and supports pre-release labels, like 2.1.7-alpha.3
         // Specify pre-release label to publish the plugin in a custom Release Channel automatically. Read more:
         // https://plugins.jetbrains.com/docs/intellij/deployment.html#specifying-a-release-channel
-        channels = properties("pluginVersion").map { listOf(it.split('-').getOrElse(1) { "default" }.split('.')[0]) }
+        channels = properties("pluginVersion").map { listOf(it.substringAfter('-').substringBefore('.').ifEmpty { "default" }) }
     }
 }