Bump org.testcontainers:testcontainers from 1.20.3 to 1.21.1

Bumps [org.testcontainers:testcontainers](https://github.com/testcontainers/testcontainers-java) from 1.20.3 to 1.21.1.
- [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...1.21.1)

---
updated-dependencies:
- dependency-name: org.testcontainers:testcontainers
  dependency-version: 1.21.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

kotlin-wot-binding-mqtt/build.gradle.kts

@@ -4,5 +4,5 @@ dependencies {
     implementation("com.hivemq:hivemq-mqtt-client:1.3.3")
     testImplementation("ch.qos.logback:logback-classic:1.5.12")
     testImplementation("app.cash.turbine:turbine:1.2.0")
-    testImplementation("org.testcontainers:testcontainers:1.20.3")
+    testImplementation("org.testcontainers:testcontainers:1.21.1")
 }