Update the Maven Central badge

Author: marcelstoer

.gitignore

@@ -10,3 +10,5 @@
 
 *.iml
 .idea
+/fly.toml
+/README-internal.adoc

README.md

@@ -1,6 +1,6 @@
 # OpenData SMN
 
-[![Maven Central](https://maven-badges.herokuapp.com/maven-central/com.frightanic/open-data-smn/badge.svg)](https://maven-badges.herokuapp.com/maven-central/com.frightanic/open-data-smn/)
+[![Maven Central Version](https://img.shields.io/maven-central/v/com.frightanic/open-data-smn)](https://central.sonatype.com/artifact/com.frightanic/open-data-smn)
 [![Docker Image Version (latest semver)](https://img.shields.io/docker/v/marcelstoer/open-data-smn?label=docker%20image)](https://hub.docker.com/r/marcelstoer/open-data-smn)
 [![License](https://img.shields.io/badge/license-MIT-blue.svg?style=flat)](https://github.com/marcelstoer/open-data-smn/blob/master/LICENSE)
 [![CI with Maven](https://github.com/marcelstoer/open-data-smn/actions/workflows/maven.yml/badge.svg?branch=master)](https://github.com/marcelstoer/open-data-smn/actions/workflows/maven.yml)