Bump xstream from 1.4.8 to 1.4.13-java7 (#27)

Bumps [xstream](https://github.com/x-stream/xstream) from 1.4.8 to 1.4.13-java7.
- [Release notes](https://github.com/x-stream/xstream/releases)
- [Commits](https://github.com/x-stream/xstream/commits)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

pom.xml

@@ -37,7 +37,7 @@
         <mapdb.version>3.0.5</mapdb.version>
         <antlr.version>3.5.2</antlr.version>
         <opencsv.version>4.2</opencsv.version>
-        <xstream.version>1.4.8</xstream.version>
+        <xstream.version>1.4.13-java7</xstream.version>
         <org.apache.commons.io.version>2.4</org.apache.commons.io.version>
     </properties>