Bump mockito-core from 2.26.0 to 2.27.0 in /core (#1382)

Bumps [mockito-core](https://github.com/mockito/mockito) from 2.26.0 to 2.27.0.
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v2.26.0...v2.27.0)

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

core/build.gradle

@@ -104,7 +104,7 @@ dependencies {
     testCompile 'redis.clients:jedis:3.0.1'
     testCompile 'com.rabbitmq:amqp-client:5.7.0'
     testCompile 'org.mongodb:mongo-java-driver:3.10.2'
-    testCompile ('org.mockito:mockito-core:2.26.0') {
+    testCompile ('org.mockito:mockito-core:2.27.0') {
         exclude(module: 'hamcrest-core')
     }
     // Synthetic JAR used for MountableFileTest and DirectoryTarResourceTest