Bump org.eclipse.rdf4j:rdf4j-bom from 5.1.5 to 5.1.6 in /rdf4j (#2343)

Author: dependabot[bot]

rdf4j/pom.xml

@@ -15,7 +15,7 @@
 
   <properties>
     <maven.compiler.release>8</maven.compiler.release>
-    <rdf4j.version>5.1.5</rdf4j.version>
+    <rdf4j.version>5.1.6</rdf4j.version>
   </properties>
 
   <dependencyManagement>