Bump XStream to 1.4.21 (#1449)

Signed-off-by: Chris Jackson <[email protected]>

Author: cdjackson

com.zsmartsystems.zigbee.console.main/pom.xml

@@ -83,7 +83,7 @@
 		<dependency>
 			<groupId>com.thoughtworks.xstream</groupId>
 			<artifactId>xstream</artifactId>
-			<version>1.4.19</version>
+			<version>1.4.21</version>
 		</dependency>
 
 	</dependencies>