bpo-35022: unittest.mock.MagicMock now also supports __fspath__ (GH-9960)

The MagicMock class supports many magic methods, but not __fspath__. To ease
testing with modules such as os.path, this function is now supported by default.
diff --git a/Doc/library/unittest.mock.rst b/Doc/library/unittest.mock.rst
index 136804c..0ae2954 100644
--- a/Doc/library/unittest.mock.rst
+++ b/Doc/library/unittest.mock.rst
@@ -1699,6 +1699,10 @@
 * Descriptor methods: ``__get__``, ``__set__`` and ``__delete__``
 * Pickling: ``__reduce__``, ``__reduce_ex__``, ``__getinitargs__``,
   ``__getnewargs__``, ``__getstate__`` and ``__setstate__``
+* File system path representation: ``__fspath__``
+
+.. versionchanged:: 3.8
+   Added support for :func:`os.PathLike.__fspath__`.
 
 
 The following methods exist but are *not* supported as they are either in use