build(gradle): Bump freefair_version from 8.14.2 to 9.1.0

Bumps `freefair_version` from 8.14.2 to 9.1.0.

Updates `io.freefair.lombok` from 8.14.2 to 9.1.0
- [Release notes](https://github.com/freefair/gradle-plugins/releases)
- [Commits](freefair/gradle-plugins@8.14.2...9.1.0)

Updates `io.freefair.javadocs` from 8.14.2 to 9.1.0
- [Release notes](https://github.com/freefair/gradle-plugins/releases)
- [Commits](freefair/gradle-plugins@8.14.2...9.1.0)

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

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

Author: dependabot[bot]

build.gradle

@@ -29,7 +29,7 @@ subprojects {
     ext.c3r_version = rootProject.file('version.txt').text.trim()
 
     // Shared dependency versions
-    ext.freefair_version = '8.14.2'
+    ext.freefair_version = '9.1.0'
     ext.junit_version = '5.14.0'
     ext.log4j_version = '2.25.2'
     ext.mockito_version = '5.2.0'