Fix tests

Author: odersky

Diff for: tests/neg/i13580.check

@@ -0,0 +1,4 @@
+-- Error: tests/neg/i13580.scala:9:7 -----------------------------------------------------------------------------------
+9 |given (using tracked val w: IntWidth) => IntCandidate: // error
+  |       ^^^^^
+  |       `using` is already implied here, should not be given explicitly

Diff for: tests/pos/i13580.scala

@@ -1,12 +1,12 @@
 //> using options -language:experimental.modularity -source future
 trait IntWidth:
   type Out
-given IntWidth with
+given IntWidth:
   type Out = 155
 
 trait IntCandidate:
   type Out
-given (using tracked val w: IntWidth): IntCandidate with
+given (tracked val w: IntWidth) => IntCandidate:
   type Out = w.Out
 
 val x = summon[IntCandidate]