Ruby: Bugfix after HTTP::Client::Request change

I guess this is not 100% accurate any longer since the base class is
only a `DataFlow::Node` now... I guess we could make it a
`DataFlow::CallNode` in the Concept definition.

Author: RasmusWL

ruby/ql/lib/codeql/ruby/security/InsecureDownloadCustomizations.qll

@@ -143,7 +143,7 @@ module InsecureDownload {
       hasUnsafeExtension(req.getAUrlPart().asExpr().getConstantValue().getString())
     }
 
-    override DataFlow::Node getDownloadCall() { result.asExpr().getExpr() = req }
+    override DataFlow::Node getDownloadCall() { result = req }
 
     override DataFlow::FlowState getALabel() {
       result instanceof Label::SensitiveInsecure
@@ -193,6 +193,6 @@ module InsecureDownload {
 
     override DataFlow::FlowState getALabel() { result instanceof Label::Insecure }
 
-    override DataFlow::Node getDownloadCall() { result.asExpr().getExpr() = request }
+    override DataFlow::Node getDownloadCall() { result = request }
   }
 }