Fix 'deecorator' typo in test/test_dataclasses (GH-5899)

diff --git a/Lib/test/test_dataclasses.py b/Lib/test/test_dataclasses.py
index ea019ae..582cb34 100755
--- a/Lib/test/test_dataclasses.py
+++ b/Lib/test/test_dataclasses.py
@@ -2411,7 +2411,7 @@
                 return 301
 
         # If frozen or eq is None, then use the default value (do not
-        # specify any value in the deecorator).
+        # specify any value in the decorator).
         for frozen, eq,    base,   expected       in [
             (None,  None,  object, 'unhashable'),
             (None,  None,  Base,   'unhashable'),