[3.10] Fix typos in the Lib directory (GH-28775) (GH-28804)

Fix typos in the Lib directory as identified by codespell.

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>.
(cherry picked from commit 745c9d9dfc1ad6fdfdf1d07420c6273ff67fa5be)

Co-authored-by: Christian Clauss <cclauss@me.com>
diff --git a/Lib/test/test_dataclasses.py b/Lib/test/test_dataclasses.py
index 33c9fcd..a1d9112 100644
--- a/Lib/test/test_dataclasses.py
+++ b/Lib/test/test_dataclasses.py
@@ -3695,7 +3695,7 @@ class B:
         with self.assertRaisesRegex(TypeError, msg):
             B(3, 4, 5)
 
-        # Explicitely make a field that follows KW_ONLY be non-keyword-only.
+        # Explicitly make a field that follows KW_ONLY be non-keyword-only.
         @dataclass
         class C:
             a: int