Bump org.apache.kafka:kafka_2.12 from 2.2.2 to 2.6.3

Bumps org.apache.kafka:kafka_2.12 from 2.2.2 to 2.6.3.

---
updated-dependencies:
- dependency-name: org.apache.kafka:kafka_2.12
  dependency-type: direct:production
...

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

pom.xml

@@ -45,7 +45,7 @@
       Kafka 0.10 API bug:
       Cannot auto-commit offsets for group ... since the coordinator is unknown
     -->
-    <kafka.version>2.2.2</kafka.version>
+    <kafka.version>2.6.3</kafka.version>
     <!-- TODO: upgrade to log4j 2 or slf4j -->
     <log4j.version>1.2.17</log4j.version>
     <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>