Java: remove unused DataFlow import

Author: Jami Cogswell

java/ql/lib/semmle/code/java/security/CsrfUnprotectedRequestTypeQuery.qll

@@ -5,7 +5,6 @@ private import semmle.code.java.frameworks.spring.SpringController
 private import semmle.code.java.frameworks.stapler.Stapler
 private import semmle.code.java.frameworks.MyBatis
 private import semmle.code.java.frameworks.Jdbc
-private import semmle.code.java.dataflow.DataFlow
 private import semmle.code.java.dataflow.ExternalFlow
 private import semmle.code.java.dispatch.VirtualDispatch
 private import semmle.code.java.dataflow.TaintTracking