Bump xstream from 1.3 to 1.4.6

Bumps xstream from 1.3 to 1.4.6.

Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/pom.xml b/pom.xml
index e4fb1e1..0398e74 100644
--- a/pom.xml
+++ b/pom.xml
@@ -117,7 +117,7 @@
         <dependency>
             <groupId>com.thoughtworks.xstream</groupId>
             <artifactId>xstream</artifactId>
-            <version>1.3</version>
+            <version>1.4.6</version>
             <optional>true</optional>
             <exclusions>
                 <exclusion>