Fix test

Author: odersky

tests/run-staging/staged-streams_1.scala

@@ -1,6 +1,8 @@
 import scala.quoted._
 import scala.quoted.staging._
 import scala.quoted.util._
+import language.experimental.namedTypeArguments
+
 /**
   * Port of the strymonas library as described in O. Kiselyov et al., Stream fusion, to completeness (POPL 2017)
   */