Small typo in https://docs.python.org/3/library/unittest.mock.html#where-to-patch

[cmarqu]

https://docs.python.org/3/library/unittest.mock.html#where-to-patch has the text "which we will have to do then it imports" which should be "which we will have to do when it imports" (i.e. s/then/when/).

The source for this is

cpython/Doc/library/unittest.mock.rst

Lines 2010 to 2011 in 3bd3e09

	:func:`patch`. The problem is that when we import module b, which we will have to
	do then it imports ``SomeClass`` from module a. If we use :func:`patch` to mock out

Linked PRs

• gh-130106: Fix a typo in unittest.mock doc #130107
• [3.13] gh-130106: Fix a typo in unittest.mock doc (GH-130107) #130143
• [3.12] gh-130106: Fix a typo in unittest.mock doc (GH-130107) #130144

[terryjreedy]

Dates back to at least 2014, so was backported.