build(deps): bump io.freefair.javadoc-utf-8 from 6.5.1 to 6.6

Bumps [io.freefair.javadoc-utf-8](https://github.com/freefair/gradle-plugins) from 6.5.1 to 6.6.
- [Release notes](https://github.com/freefair/gradle-plugins/releases)
- [Commits](freefair/gradle-plugins@6.5.1...6.6)

---
updated-dependencies:
- dependency-name: io.freefair.javadoc-utf-8
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

build.gradle.kts

@@ -11,7 +11,7 @@ plugins {
     id("org.sonarqube") version "3.5.0.2730"
     id("io.freefair.lombok") version "6.5.1"
     id("io.freefair.javadoc-links") version "6.5.1"
-    id("io.freefair.javadoc-utf-8") version "6.5.1"
+    id("io.freefair.javadoc-utf-8") version "6.6"
     id("io.freefair.aspectj.post-compile-weaving") version "6.5.1"
     id("io.freefair.maven-central.validate-poms") version "6.5.1"
     id("me.qoomon.git-versioning") version "6.3.6"