chore(deps): bump org.mockito:mockito-core in /java-8

Bumps [org.mockito:mockito-core](https://github.com/mockito/mockito) from 5.19.0 to 5.21.0.
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v5.19.0...v5.21.0)

---
updated-dependencies:
- dependency-name: org.mockito:mockito-core
  dependency-version: 5.21.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

gradle/dependencies.gradle

@@ -2,7 +2,7 @@ dependencies {
     // Use JUnit test framework
     testImplementation 'org.junit.jupiter:junit-jupiter:5.13.4'
     testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
-    testImplementation 'org.mockito:mockito-core:5.19.0'
+    testImplementation 'org.mockito:mockito-core:5.21.0'
     testImplementation 'io.opentelemetry:opentelemetry-api:1.54.0'
     testImplementation 'io.opentelemetry:opentelemetry-context:1.54.0'
     testImplementation 'io.github.std-uritemplate:std-uritemplate:1.0.6'