docs: fix maven badge

the old link doesn't work anymore

Author: FSchumacher

README.md

@@ -8,7 +8,7 @@ By The Apache Software Foundation
 [![codecov](https://codecov.io/gh/apache/jmeter/branch/master/graph/badge.svg)](https://codecov.io/gh/apache/jmeter)
 [![License](https://img.shields.io/:license-apache-brightgreen.svg)](https://www.apache.org/licenses/LICENSE-2.0.html)
 [![Stack Overflow](https://img.shields.io/:stack%20overflow-jmeter-brightgreen.svg)](https://stackoverflow.com/questions/tagged/jmeter)
-[![Maven Central](https://maven-badges.herokuapp.com/maven-central/org.apache.jmeter/ApacheJMeter/badge.svg)](https://maven-badges.herokuapp.com/maven-central/org.apache.jmeter/ApacheJMeter)
+[![Maven Central](https://img.shields.io/maven-central/v/org.apache.jmeter/ApacheJMeter.svg?label=Maven%20Central)](https://search.maven.org/artifact/org.apache.jmeter/ApacheJMeter)
 [![Javadocs](https://www.javadoc.io/badge/org.apache.jmeter/ApacheJMeter_core.svg)](https://www.javadoc.io/doc/org.apache.jmeter/ApacheJMeter_core)
 [![Twitter](https://img.shields.io/twitter/url/https/github.com/apache/jmeter.svg?style=social)](https://twitter.com/intent/tweet?text=Powerful%20load%20testing%20with%20Apache%20JMeter:&url=https://jmeter.apache.org)