Make scala.caps.Pure non-experimental

Author: natsukagami

library/src/scala/caps/Pure.scala

@@ -1,10 +1,9 @@
 package scala
 package caps
-import annotation.experimental
 
 /** A marker trait that declares that all inheriting classes are "pure" in the
  *  sense that their values retain no capabilities including capabilities needed
  *  to perform effects. This has formal meaning only under capture checking.
  */
-@experimental trait Pure:
+trait Pure:
   this: Pure =>

tests/run-tasty-inspector/stdlibExperimentalDefinitions.scala

@@ -30,7 +30,6 @@ val experimentalDefinitionInLibrary = Set(
   "scala.annotation.retains",
   "scala.annotation.retainsByName",
   "scala.annotation.retainsCap",
-  "scala.Pure",
   "scala.caps.CapSet",
   "scala.caps.Contains",
   "scala.caps.Contains$",