Bump org.mockito:mockito-core from 5.5.0 to 5.6.0 (#618)

Bumps [org.mockito:mockito-core](https://github.com/mockito/mockito) from 5.5.0 to 5.6.0.
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v5.5.0...v5.6.0)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

cli/build.gradle

@@ -15,7 +15,7 @@ dependencies {
     implementation group: 'org.apache.logging.log4j', name: 'log4j-api', version: '2.20.0'
     implementation group: 'org.apache.logging.log4j', name: 'log4j-core', version: '2.20.0'
 
-    testImplementation "org.mockito:mockito-core:5.5.0"
+    testImplementation "org.mockito:mockito-core:5.6.0"
 }
 
 mainClassName = 'org.openapitools.openapistylevalidator.cli.Main'