Drop unnecessary import (#316)

Signed-off-by: Sven Strickroth <email@cs-ware.de>

Author: csware

src/main/java/org/owasp/html/HtmlPolicyBuilder.java

@@ -32,7 +32,6 @@
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
-import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;