chore: make the stdlib compile because of stale symbols

Author: hamzaremmal

library/src/scala/Conversion.scala

@@ -38,11 +38,11 @@ object Conversion:
    *  conversions are tried from the type of `t` to `T`. `into[T]` types are erased to `T`
    *  in all covariant positions of the types of parameter symbols.
    */
-  @experimental
-  opaque type into[+T] >: T = T
+  //@experimental
+  //opaque type into[+T] >: T = T
 
   /** Unwrap an `into` */
-  extension [T](x: into[T])
-    @experimental def underlying: T = x
+  //extension [T](x: into[T])
+  //  @experimental def underlying: T = x
 
 end Conversion