Correct a typo in the Unittest documentation (GH-10397)


Co-Authored-By: maggyero <gery.ogam@gmail.com>
(cherry picked from commit 009b2f02049eda3b29d4f4f743e51df106686375)

Co-authored-by: Géry Ogam <gery.ogam@gmail.com>
diff --git a/Doc/library/unittest.rst b/Doc/library/unittest.rst
index 1153459..fb5bd2b 100644
--- a/Doc/library/unittest.rst
+++ b/Doc/library/unittest.rst
@@ -607,7 +607,7 @@
 
 .. versionadded:: 3.4
 
-When some of your tests differ only by a some very small differences, for
+When there are very small differences among your tests, for
 instance some parameters, unittest allows you to distinguish them inside
 the body of a test method using the :meth:`~TestCase.subTest` context manager.