Upgrade httpclient to 4.5.9

Fixes gh-7138

[closes #7138]

gradle/dependency-management.gradle

@@ -128,7 +128,7 @@ dependencyManagement {
 		dependency 'org.apache.directory.shared:shared-cursor:0.9.15'
 		dependency 'org.apache.directory.shared:shared-ldap-constants:0.9.15'
 		dependency 'org.apache.directory.shared:shared-ldap:0.9.15'
-		dependency 'org.apache.httpcomponents:httpclient:4.5.8'
+		dependency 'org.apache.httpcomponents:httpclient:4.5.9'
 		dependency 'org.apache.httpcomponents:httpcore:4.4.8'
 		dependency 'org.apache.httpcomponents:httpmime:4.5.3'
 		dependency 'org.apache.mina:mina-core:2.0.0-M6'