Remove version from Maven Central badge URL

Sonatype released changes allowing links to Maven Central to include
only the groupId and artifactId without having to specify the version.

see: https://issues.sonatype.org/browse/MVNCENTRAL-7923

README.md

@@ -2,6 +2,6 @@
 [![Build](https://github.com/kiwiproject/kiwi-parent/workflows/build/badge.svg)](https://github.com/kiwiproject/kiwi-parent/actions?query=workflow%3Abuild)
 [![Quality Gate Status](https://sonarcloud.io/api/project_badges/measure?project=kiwiproject_kiwi-parent&metric=alert_status)](https://sonarcloud.io/dashboard?id=kiwiproject_kiwi-parent)
 [![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](https://opensource.org/licenses/MIT)
-[![Maven Central](https://img.shields.io/maven-central/v/org.kiwiproject/kiwi-parent)](https://central.sonatype.com/artifact/org.kiwiproject/kiwi-parent/2.0.15)
+[![Maven Central](https://img.shields.io/maven-central/v/org.kiwiproject/kiwi-parent)](https://central.sonatype.com/artifact/org.kiwiproject/kiwi-parent/)
 
 This is a parent POM for use by projects in the Kiwi Project organization.