chore(deps): Bump mockito in /pbj-core/hiero-dependency-versions

Bumps `mockito` from 5.10.0 to 5.15.2.

Updates `org.mockito:mockito-core` from 5.10.0 to 5.15.2
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v5.10.0...v5.15.2)

Updates `org.mockito:mockito-junit-jupiter` from 5.10.0 to 5.15.2
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v5.10.0...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] <support@github.com>

pbj-core/hiero-dependency-versions/build.gradle.kts

@@ -29,7 +29,7 @@ val helidon = "4.1.6"
 val protobuf = "4.28.2"
 
 val junit5 = "5.11.4"
-val mockito = "5.10.0"
+val mockito = "5.15.2"
 
 dependencies.constraints {
     api("org.antlr:antlr4-runtime:$antlr") { because("org.antlr.antlr4.runtime") }