Bump org.assertj:assertj-core from 2.6.0 to 2.9.1

Bumps [org.assertj:assertj-core](https://github.com/joel-costigliola/assertj-core) from 2.6.0 to 2.9.1.
- [Release notes](https://github.com/joel-costigliola/assertj-core/releases)
- [Commits](assertj/assertj@assertj-core-2.6.0...assertj-core-2.9.1)

---
updated-dependencies:
- dependency-name: org.assertj:assertj-core
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

build.gradle

@@ -712,7 +712,7 @@ subprojects {
 
             dependency "org.junit.jupiter:junit-jupiter:5.10.2"
             dependency "org.junit-pioneer:junit-pioneer:1.9.1"
-            dependency "org.assertj:assertj-core:2.8.0"
+            dependency "org.assertj:assertj-core:2.9.1"
 
             dependency "org.mockito:mockito-core:${mockitoVersion}"
             dependency "org.mockito:mockito-inline:${mockitoVersion}"