fix: adapt tests/neg-custom-args/captures/i15772.scala to the cc library

Author: hamzaremmal

tests/neg-custom-args/captures/i15772.check

@@ -1,3 +1,7 @@
+-- Error: tests/neg-custom-args/captures/i15772.scala:44:18 ------------------------------------------------------------
+44 |  val filesList : List[File]^{io} = ??? // error
+   |                  ^^^^^^^^^^^^^^^
+   |                  List[File] is a pure type, it makes no sense to add a capture set to it
 -- Error: tests/neg-custom-args/captures/i15772.scala:22:46 ------------------------------------------------------------
 22 |    val boxed1 : ((C^) => Unit) -> Unit = box1(c)  // error
    |                                          ^^^^^^^

tests/neg-custom-args/captures/i15772.scala

@@ -41,6 +41,6 @@ trait File:
 
 def main(io: Any^) =
   val sayHello: ((File^{io}) => Unit) = (file: File^{io}) => file.write("Hello World!\r\n")
-  val filesList : List[File]^{io} = ???
+  val filesList : List[File]^{io} = ??? // error
   val x = () => filesList.foreach(sayHello)
   x: (() -> Unit) // error