[SQL] Fix non-ASCII em dash in SortExec.rowSorter warning comment

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: viirya

sql/core/src/main/scala/org/apache/spark/sql/execution/SortExec.scala

@@ -63,7 +63,7 @@ case class SortExec(
     "spillSize" -> SQLMetrics.createSizeMetric(sparkContext, "spill size"))
 
   // WARNING: This is a shared mutable var on the SortExec instance. Do not access it from
-  // multiple threads concurrently — Spark operators do not guarantee thread-safety and one
+  // multiple threads concurrently - Spark operators do not guarantee thread-safety and one
   // task's sorter could overwrite another's, causing a race condition.
   private[sql] var rowSorter: UnsafeExternalRowSorter = _