Bump the removal to 3.9, indicate collections.abc available since 3.3,
replace version-changed directive to deprecated-removed.
https://bugs.python.org/issue36953
* BPO-27639: Correct return type for UserList slicing operation
Added logic to __getitem__ magic method for UserList to ensure that the return
type matches that of self.
* bpo-32492: 2.5x speed up in namedtuple attribute access using C fast path
* Add News entry
* fixup! bpo-32492: 2.5x speed up in namedtuple attribute access using C fast path
* Check for tuple in the __get__ of the new descriptor and don't cache the descriptor itself
* Don't inherit from property. Implement GC methods to handle __doc__
* Add a test for the docstring substitution in descriptors
* Update NEWS entry to reflect time against 3.7 branch
* Simplify implementation with argument clinic, better error messages, only __new__
* Use positional-only parameters for the __new__
* Use PyTuple_GET_SIZE and PyTuple_GET_ITEM to tighter the implementation of tuplegetterdescr_get
* Implement __set__ to make tuplegetter a data descriptor
* Use Py_INCREF now that we inline PyTuple_GetItem
* Apply the valid_index() function, saving one test
* Move Py_None test out of the critical path.
* Working draft without _source
* Re-use itemgetter() instances
* Speed-up calls to __new__() with a pre-bound tuple.__new__()
* Add note regarding string interning
* Remove unnecessary create function wrappers
* Minor sync-ups with PR-2736. Mostly formatting and f-strings
* Bring-in qualname/__module fix-ups from PR-2736
* Formally remove the verbose flag and _source attribute
* Restore a test of potentially problematic field names
* Restore kwonly_args test but without the verbose option
* Adopt Inada's idea to reuse the docstrings for the itemgetters
* Neaten-up a bit
* Add news blurb
* Serhiy pointed-out the need for interning
* Jelle noticed as missing f on an f-string
* Add whatsnew entry for feature removal
* Accede to request for dict literals instead keyword arguments
* Leave the method.__module__ attribute pointing the actual location of the code
* Improve variable names and add a micro-optimization for an non-public helper function
* Simplify by in-lining reuse_itemgetter()
* Arrange steps in more logical order
* Save docstring in local cache instead of interning
* fixed OrderedDict.__init__ docstring re PEP 468
* tightened comment and mirrored to C impl
* added space after period per marco-buttu
* preserved substituted for stable
* drop references to Python 3.6 and PEP 468