Bump io.freefair.aggregate-javadoc from 6.6.3 to 8.6

Bumps [io.freefair.aggregate-javadoc](https://github.com/freefair/gradle-plugins) from 6.6.3 to 8.6.
- [Release notes](https://github.com/freefair/gradle-plugins/releases)
- [Commits](freefair/gradle-plugins@6.6.3...8.6)

---
updated-dependencies:
- dependency-name: io.freefair.aggregate-javadoc
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

settings.gradle

@@ -15,7 +15,7 @@ pluginManagement {
         gradlePluginPortal()
     }
     plugins {
-        id "io.freefair.aggregate-javadoc" version "6.6.3"
+        id "io.freefair.aggregate-javadoc" version "8.6"
         id "io.freefair.lombok" version "8.6"
         // Checks for unnecessary dependencies
         id("com.autonomousapps.dependency-analysis") version "1.32.0"