fix testcases

Author: Porcuiney Hairs

csharp/ql/test/experimental/CWE-918/RequestForgery.expected

@@ -3,5 +3,6 @@ edges
 nodes
 | RequestForgery.cs:14:52:14:54 | url : String | semmle.label | url : String |
 | RequestForgery.cs:16:66:16:68 | access to parameter url | semmle.label | access to parameter url |
+subpaths
 #select
 | RequestForgery.cs:16:66:16:68 | access to parameter url | RequestForgery.cs:14:52:14:54 | url : String | RequestForgery.cs:16:66:16:68 | access to parameter url | $@ flows to here and is used in a method of WebClient. | RequestForgery.cs:14:52:14:54 | url | User-provided value |