Fixing maven central badge

Author: coheigea

README.md

@@ -1,5 +1,5 @@
 [![Build Status](https://builds.apache.org/job/santuario/job/Santuario-Java-main-JDK11/badge/icon?subject=Build)](https://builds.apache.org/job/Santuario/job/Santuario-Java-main-JDK11/)
-[![Maven Central](https://maven-badges.herokuapp.com/maven-central/org.apache.santuario/xmlsec/badge.svg)](https://maven-badges.herokuapp.com/maven-central/org.apache.santuario/xmlsec)
+[![Maven Central](https://maven-badges.sml.io/maven-central/org.apache.santuario/xmlsec/badge.svg)](https://maven-badges.sml.io/maven-central/org.apache.santuario/xmlsec)
 [![OpenSSF Scorecard](https://api.securityscorecards.dev/projects/github.com/apache/santuario-xml-security-java/badge)](https://api.securityscorecards.dev/projects/github.com/apache/santuario-xml-security-java)
 [![OpenSSF Best Practices](https://bestpractices.coreinfrastructure.org/projects/6932/badge)](https://bestpractices.coreinfrastructure.org/projects/6932)