Fix typo in dataclasses module (GH-21109)



Automerge-Triggered-By: @matrixise
diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index fc69508..530d3e9 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1094,7 +1094,7 @@
         # method, because:
         # - it does not recurse in to the namedtuple fields and
         #   convert them to dicts (using dict_factory).
-        # - I don't actually want to return a dict here.  The the main
+        # - I don't actually want to return a dict here.  The main
         #   use case here is json.dumps, and it handles converting
         #   namedtuples to lists.  Admittedly we're losing some
         #   information here when we produce a json list instead of a