Bump mockito from 5.14.2 to 5.15.2 in /service

Bumps `mockito` from 5.14.2 to 5.15.2.

Updates `org.mockito:mockito-core` from 5.14.2 to 5.15.2
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v5.14.2...v5.15.2)

Updates `org.mockito:mockito-junit-jupiter` from 5.14.2 to 5.15.2
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v5.14.2...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]>

service/gradle/libs.versions.toml

@@ -13,7 +13,7 @@ kotlin = "2.1.0"
 ktfmt = "0.21.0"
 ktlint = "1.5.0"
 ktlint-gradle = "12.1.0"
-mockito = "5.14.2"
+mockito = "5.15.2"
 owasp = "11.1.0"
 spring-boot = "3.4.1"
 versions = "0.51.0"