Bump io.freefair.maven-central.validate-poms from 8.3 to 8.4

Bumps [io.freefair.maven-central.validate-poms](https://github.com/freefair/gradle-plugins) from 8.3 to 8.4.
- [Release notes](https://github.com/freefair/gradle-plugins/releases)
- [Commits](freefair/gradle-plugins@8.3...8.4)

---
updated-dependencies:
- dependency-name: io.freefair.maven-central.validate-poms
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

build.gradle.kts

@@ -2,7 +2,7 @@ plugins {
   id("maven-publish")
   id("com.github.ben-manes.versions") version "0.49.0"
   id("net.ossindex.audit") version "0.4.11"
-  id("io.freefair.maven-central.validate-poms") version "8.3"
+  id("io.freefair.maven-central.validate-poms") version "8.4"
   id("io.github.gradle-nexus.publish-plugin") version "1.3.0"
 }