MINOR: Update Scala to 2.13.8 in gradle.properties
It was updated in dependencies.gradle but this one was probably left out.
Reviewers: Ismael Juma Andras Katona
@@ -21,7 +21,7 @@ group=org.apache.kafka
# - tests/kafkatest/version.py (variable DEV_VERSION)
# - kafka-merge-pr.py
version=3.3.0-SNAPSHOT
-scalaVersion=2.13.6
+scalaVersion=2.13.8
task=build
org.gradle.jvmargs=-Xmx2g -Xss4m -XX:+UseParallelGC
org.gradle.parallel=true
