build: drop ktlint plugin from version catalog

We don't use it anymore.

Author: languitar

gradle/libs.versions.toml

@@ -11,7 +11,6 @@ kotlin-multiplatform = { id = "org.jetbrains.kotlin.multiplatform", version.ref
 kotlin-jvm = { id = "org.jetbrains.kotlin.jvm", version.ref = "kotlin" }
 kotlin-serialization = { id = "org.jetbrains.kotlin.plugin.serialization", version.ref = "kotlin" }
 gitVersion = { id = "com.palantir.git-version", version = "3.0.0" }
-ktlint = { id = "org.jlleitschuh.gradle.ktlint", version = "12.1.0" }
 spotless = { id = "com.diffplug.spotless", version = "6.25.0" }
 modelix-mps-buildtools = { id = "org.modelix.mps.build-tools", version.ref = "modelixBuildtools" }
 dokka = {id = "org.jetbrains.dokka", version.ref = "dokka"}