Bump mockito-core from 3.2.0 to 3.2.4 in /core (#2186)

Bumps [mockito-core](https://github.com/mockito/mockito) from 3.2.0 to 3.2.4.
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v3.2.0...v3.2.4)

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

Co-authored-by: null <27856297+dependabot-preview[bot]@users.noreply.github.com>

core/build.gradle

@@ -109,7 +109,7 @@ dependencies {
     testCompile 'redis.clients:jedis:3.2.0'
     testCompile 'com.rabbitmq:amqp-client:5.8.0'
     testCompile 'org.mongodb:mongo-java-driver:3.12.0'
-    testCompile ('org.mockito:mockito-core:3.2.0') {
+    testCompile ('org.mockito:mockito-core:3.2.4') {
         exclude(module: 'hamcrest-core')
     }
     // Synthetic JAR used for MountableFileTest and DirectoryTarResourceTest