remove unused import

Author: Vladimir Kotal

opengrok-web/src/test/java/org/opengrok/web/api/v1/controller/SystemControllerTest.java

@@ -43,7 +43,6 @@
 import java.nio.file.Paths;
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
-import java.util.Calendar;
 import java.util.Date;
 
 import static org.hamcrest.Matchers.containsString;