Move xstream.version property to test dependencies section

XStream is only used for tests, and is not an optional
production dependency. This commit moves the property
declaration to the correct section in the pom file.

Author: fmbenhassine

pom.xml

@@ -76,11 +76,11 @@
 		<jakarta.persistence-api.version>3.1.0</jakarta.persistence-api.version>
 		<neo4j-ogm-core.version>3.2.37</neo4j-ogm-core.version>
 		<mongodb-driver-sync.version>4.7.1</mongodb-driver-sync.version>
-		<xstream.version>1.4.19</xstream.version>
 		<junit-jupiter.version>5.8.2</junit-jupiter.version>
 
 		<!-- test dependencies -->
 		<micrometer-tracing.version>1.0.0-SNAPSHOT</micrometer-tracing.version>
+		<xstream.version>1.4.19</xstream.version>
 		<junit.version>4.13.2</junit.version>
 		<junit-vintage-engine.version>${junit-jupiter.version}</junit-vintage-engine.version>
 		<hamcrest.version>2.2</hamcrest.version>