Bump org.mockito:mockito-core from 5.12.0 to 5.13.0

Bumps [org.mockito:mockito-core](https://github.com/mockito/mockito) from 5.12.0 to 5.13.0.
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v5.12.0...v5.13.0)

---
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]>

build.gradle

@@ -55,7 +55,7 @@ java {
 ext {
     deps = [
         gocdPluginApi: 'cd.go.plugin:go-plugin-api:24.3.0',
-        mockito      : 'org.mockito:mockito-core:5.12.0',
+        mockito      : 'org.mockito:mockito-core:5.13.0',
     ]
 
     versions = project.ext.deps.collectEntries { lib, libGav -> [lib, libGav.split(':').last()] }