Bump org.jetbrains.intellij from 1.5.2 to 1.8.1

Bumps org.jetbrains.intellij from 1.5.2 to 1.8.1.

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

build.gradle.kts

@@ -22,7 +22,7 @@ plugins {
     // Kotlin support
     id("org.jetbrains.kotlin.jvm") version "1.5.31"
     // Gradle IntelliJ Plugin
-    id("org.jetbrains.intellij") version "1.5.2"
+    id("org.jetbrains.intellij") version "1.8.1"
     // Gradle Changelog Plugin
     id("org.jetbrains.changelog") version "1.3.0"