Remove dead code from upload example:

This is a port of a commit by racke (GH #1329).

Author: xsawyerx

lib/Dancer2/Manual.pod

@@ -1399,7 +1399,7 @@ The objects are accessible within the route handlers using the C<upload>
 keyword:
 
     post '/upload' => sub {
-        my $upload     = upload('file_input_name');    # upload object
+        my $upload = upload('file_input_name'); # upload object
         $upload->copy_to('Uploads/');
     };