gh-62480: De-personalize "Partial mocking" section in unittest.mock examples (#141321)

* Refine some wording in unittest partial mock doc

Some of the descriptions were addressed in first person,
but have now been changed to address the user reading the documentation instead.

Co-authored-by: C.A.M. Gerlach <CAM.Gerlach@Gerlach.CAM>

Doc/library/unittest.mock-examples.rst

@@ -600,13 +600,13 @@ this list of calls for us::
 Partial mocking
 ~~~~~~~~~~~~~~~
 
-In some tests I wanted to mock out a call to :meth:`datetime.date.today`
+For some tests, you may want to mock out a call to :meth:`datetime.date.today`
-to return a known date, but I didn't want to prevent the code under test from
+to return a known date, but don't want to prevent the code under test from
-creating new date objects. Unfortunately :class:`datetime.date` is written in C, and
+creating new date objects. Unfortunately :class:`datetime.date` is written in C,
-so I couldn't just monkey-patch out the static :meth:`datetime.date.today` method.
+so you cannot just monkey-patch out the static :meth:`datetime.date.today` method.
 
-I found a simple way of doing this that involved effectively wrapping the date
+Instead, you can effectively wrap the date
-class with a mock, but passing through calls to the constructor to the real
+class with a mock, while passing through calls to the constructor to the real
 class (and returning real instances).
 
 The :func:`patch decorator <patch>` is used here to