Bump assertj-core from 3.14.0 to 3.19.0 in /examples

Bumps [assertj-core](https://github.com/assertj/assertj-core) from 3.14.0 to 3.19.0.
- [Release notes](https://github.com/assertj/assertj-core/releases)
- [Commits](assertj/assertj@assertj-core-3.14.0...assertj-core-3.19.0)

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

examples/kafka-cluster/build.gradle

@@ -11,7 +11,7 @@ dependencies {
     testAnnotationProcessor "org.projectlombok:lombok:1.18.10"
     testCompile 'org.testcontainers:kafka'
     testCompile 'org.apache.kafka:kafka-clients:2.3.1'
-    testCompile 'org.assertj:assertj-core:3.14.0'
+    testCompile 'org.assertj:assertj-core:3.19.0'
     testCompile 'com.google.guava:guava:23.0'
     testCompile 'org.slf4j:slf4j-simple:1.7.30'
 }