Upgrade to scala-library 2.13.1

This allows us to revert 3d13696 and
71a022c.

Author: smarter

compiler/src/dotty/tools/dotc/ast/Trees.scala

@@ -362,16 +362,13 @@ object Trees {
           val nameStart =
             if (point != span.start) point
             else {
-              // Use an immutable ArraySeq to work around https://github.com/scala/bug/issues/11708
-              val content = collection.immutable.ArraySeq.unsafeWrapArray(source.content())
-
               // Point might be too far away from start to be recorded. In this case we fall back to scanning
               // forwards from the start offset for the name.
               // Note: This might be inaccurate since scanning might hit accidentally the same
               // name (e.g. in a comment) before finding the real definition.
               // To make this behavior more robust we'd have to change the trees for definitions to contain
               // a fully positioned Ident in place of a name.
-              val idx = content.indexOfSlice(realName, point)
+              val idx = source.content().indexOfSlice(realName, point)
               if (idx >= 0) idx
               else point // use `point` anyway. This is important if no source exists so scanning fails
             }

project/Build.scala

@@ -77,8 +77,8 @@ object Build {
    *  scala-library.
    */
   def stdlibVersion(implicit mode: Mode): String = mode match {
-    case NonBootstrapped => "2.13.0"
-    case Bootstrapped => "2.13.0"
+    case NonBootstrapped => "2.13.1"
+    case Bootstrapped => "2.13.1"
   }
 
   val dottyOrganization = "ch.epfl.lamp"