Bump org.jetbrains.intellij from 1.9.0 to 1.15.0

Bumps org.jetbrains.intellij from 1.9.0 to 1.15.0.

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

Signed-off-by: dependabot[bot] <support@github.com>

build.gradle

@@ -18,7 +18,7 @@ plugins {
     id 'checkstyle'
     id 'codenarc'
     id 'me.champeau.gradle.jmh' version '0.5.3'
-    id 'org.jetbrains.intellij' version '1.9.0'
+    id 'org.jetbrains.intellij' version '1.15.0'
     id 'net.saliman.cobertura' version '4.0.0'
     id 'com.github.ben-manes.versions' version '0.46.0'
     id 'net.ltgt.errorprone' version '2.0.2'