Added missing import for UnsupportedEncodingException

src/main/java/de/landsh/opendata/csw2dcat/MDMetadata2Dataset.java

@@ -25,6 +25,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
+import java.io.UnsupportedEncodingException;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLEncoder;