build(deps): Bump org.testcontainers:kafka in /sample-apps/kafka-app

Bumps [org.testcontainers:kafka](https://github.com/testcontainers/testcontainers-java) from 1.20.3 to 1.20.4.
- [Release notes](https://github.com/testcontainers/testcontainers-java/releases)
- [Changelog](https://github.com/testcontainers/testcontainers-java/blob/main/CHANGELOG.md)
- [Commits](testcontainers/testcontainers-java@1.20.3...1.20.4)

---
updated-dependencies:
- dependency-name: org.testcontainers:kafka
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

sample-apps/kafka-app/build.gradle

@@ -12,7 +12,7 @@ dependencies {
   testImplementation project(':microshed-testing-testcontainers')
 
   testImplementation 'org.awaitility:awaitility:4.2.2'
-  testImplementation 'org.testcontainers:kafka:1.20.3'
+  testImplementation 'org.testcontainers:kafka:1.20.4'
   testImplementation 'org.slf4j:slf4j-log4j12:2.0.16'
 
   testImplementation 'org.junit.jupiter:junit-jupiter:5.11.3'