Bump io.freefair.aggregate-javadoc from 6.6.3 to 9.1.0

Bumps [io.freefair.aggregate-javadoc](https://github.com/freefair/gradle-plugins) from 6.6.3 to 9.1.0.
- [Release notes](https://github.com/freefair/gradle-plugins/releases)
- [Commits](freefair/gradle-plugins@6.6.3...9.1.0)

---
updated-dependencies:
- dependency-name: io.freefair.aggregate-javadoc
  dependency-version: 9.1.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

settings.gradle

@@ -16,7 +16,7 @@ pluginManagement {
     }
     plugins {
         // problem when upgraded to version "9.0.0"
-        id "io.freefair.aggregate-javadoc" version "6.6.3"
+        id "io.freefair.aggregate-javadoc" version "9.1.0"
         // Checks for unnecessary dependencies
         id("com.autonomousapps.dependency-analysis") version "1.32.0"
         // helps resolve log implementation clashes