Adapt error message explanation to use .runtimeChecked

Author: odersky

compiler/src/dotty/tools/dotc/reporting/messages.scala

@@ -922,7 +922,7 @@ class UncheckedTypePattern(argType: Type, whyNot: String)(using Context)
     i"""|Type arguments and type refinements are erased during compile time, thus it's
         |impossible to check them at run-time.
         |
-        |You can either replace the type arguments by ${hl("_")} or use `@unchecked`.
+        |You can either replace the type arguments by ${hl("_")} or use `.runtimeChecked`.
         |"""
 }
 
@@ -3518,7 +3518,7 @@ final class OnlyFullyDependentAppliedConstructorType()(using Context)
   override protected def explain(using Context): String = ""
 
 final class IllegalContextBounds(using Context) extends SyntaxMsg(IllegalContextBoundsID):
-  override protected def msg(using Context): String = 
+  override protected def msg(using Context): String =
     i"Context bounds are not allowed in this position"
 
   override protected def explain(using Context): String = ""