Bump quarkus.platform.version

Bumps `quarkus.platform.version` from 3.19.4 to 3.21.0.

Updates `io.quarkus.platform:quarkus-bom` from 3.19.4 to 3.21.0
- [Commits](quarkusio/quarkus-platform@3.19.4...3.21.0)

Updates `io.quarkus.platform:quarkus-maven-plugin` from 3.19.4 to 3.21.0
- [Commits](quarkusio/quarkus-platform@3.19.4...3.21.0)

---
updated-dependencies:
- dependency-name: io.quarkus.platform:quarkus-bom
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: io.quarkus.platform:quarkus-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

kafka-exercises-solutions/6.2-java-avro-clients/quarkus-avro-consumer/pom.xml

@@ -13,7 +13,7 @@
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
         <quarkus.platform.artifact-id>quarkus-bom</quarkus.platform.artifact-id>
         <quarkus.platform.group-id>io.quarkus.platform</quarkus.platform.group-id>
-        <quarkus.platform.version>3.19.4</quarkus.platform.version>
+        <quarkus.platform.version>3.21.0</quarkus.platform.version>
         <skipITs>true</skipITs>
         <surefire-plugin.version>3.5.2</surefire-plugin.version>
     </properties>