build(deps): bump mockito in /hiero-dependency-versions

Bumps `mockito` from 5.8.0 to 5.15.2.

Updates `org.mockito:mockito-core` from 5.8.0 to 5.15.2
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v5.8.0...v5.15.2)

Updates `org.mockito:mockito-junit-jupiter` from 5.8.0 to 5.15.2
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v5.8.0...v5.15.2)

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

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

hiero-dependency-versions/build.gradle.kts

@@ -41,7 +41,7 @@ val helidon = "4.1.6"
 val jackson = "2.16.0"
 val junit5 = "5.10.2"
 val log4j = "2.21.1"
-val mockito = "5.8.0"
+val mockito = "5.15.2"
 val protobuf = "4.28.2"
 val testContainers = "1.20.4"
 val tuweni = "2.4.2"