MINOR: Update minimum required Gradle version to 4.7
After commit the minimum required gradle version changed to 4.7
This is due to the use of isJava11Compatible() in build.gradle. It was
introduced in version 4.7 (https://github.com/gradle/gradle/blob/master/subprojects/base-services/src/main/java/org/gradle/api/JavaVersion.java#L172-L180)
Reviewers: Ismael Juma
@@ -4,7 +4,7 @@ See our [web site](http://kafka.apache.org) for details on the project.
You need to have [Gradle](http://www.gradle.org/installation) and [Java](http://www.oracle.com/technetwork/java/javase/downloads/index.html) installed.
-Kafka requires Gradle 4.6 or higher.
+Kafka requires Gradle 4.7 or higher.
Java 8 should be used for building in order to support both Java 8 and Java 10 at runtime.
