Bump io.freefair.lombok from 6.0.0-m2 to 8.4

Bumps [io.freefair.lombok](https://github.com/freefair/gradle-plugins) from 6.0.0-m2 to 8.4.
- [Release notes](https://github.com/freefair/gradle-plugins/releases)
- [Commits](freefair/gradle-plugins@6.0.0-m2...8.4)

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

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

build.gradle

@@ -8,7 +8,7 @@ plugins {
     id 'java'
     id 'application'
     id 'kr.entree.spigradle' version '2.4.3'
-    id "io.freefair.lombok" version "6.0.0-m2"
+    id "io.freefair.lombok" version "8.4"
     id 'com.github.johnrengelman.shadow' version '7.1.2'
 }