build(deps): bump org.eclipse.rdf4j:rdf4j-bom in /backend

Bumps [org.eclipse.rdf4j:rdf4j-bom](https://github.com/eclipse/rdf4j) from 4.3.3 to 4.3.9.
- [Release notes](https://github.com/eclipse/rdf4j/releases)
- [Commits](eclipse-rdf4j/rdf4j@4.3.3...4.3.9)

---
updated-dependencies:
- dependency-name: org.eclipse.rdf4j:rdf4j-bom
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

backend/pom.xml

@@ -33,7 +33,7 @@
 
         <!-- RDF4J -->
         <apache.jena.version>4.10.0</apache.jena.version>
-        <eclipse.rdf4j.version>4.3.3</eclipse.rdf4j.version>
+        <eclipse.rdf4j.version>4.3.9</eclipse.rdf4j.version>
 
         <!-- LOGGING -->
         <slf4j-api.version>2.0.7</slf4j-api.version>