Update htmlunit to 2.52.0

Closes spring-projectsgh-10201

Author: rwinch

dependencies/spring-security-dependencies.gradle

@@ -35,7 +35,7 @@ dependencies {
 		api "javax.xml.bind:jaxb-api:2.3.1"
 		api "ldapsdk:ldapsdk:4.1"
 		api "net.sf.ehcache:ehcache:2.10.9.2"
-		api "net.sourceforge.htmlunit:htmlunit:2.51.0"
+		api "net.sourceforge.htmlunit:htmlunit:2.52.0"
 		api "net.sourceforge.nekohtml:nekohtml:1.9.22"
 		api "org.apache.directory.server:apacheds-core-entry:1.5.5"
 		api "org.apache.directory.server:apacheds-core:1.5.5"