Add official support for Python 3.12 / Pip 23.2. #1987

Job	Run time
Check GitHub Organization	3s
(macos-12) Pip 20 TOXENV=py311	23m 50s
(ubuntu-22.04) Pip 20 TOXENV=py311	15m 46s
(ubuntu-22.04) Pip 22_3_1 TOXENV=py311	16m 4s
(ubuntu-22.04) Pip 23_1_2 TOXENV=py311	20m 13s
(macos-12) Pip 23_2 TOXENV=py312	24m 29s
(ubuntu-22.04) Pip 23_2 TOXENV=py312	14m 18s
TOXENV=format-check,typecheck,vendor-check,package -- --additional-format sdist --additional-form...	5m 23s
(macos-12) Pip 20 TOXENV=py27-integration	53m 7s
(ubuntu-22.04) Pip 20 TOXENV=py27-integration	29m 47s
(ubuntu-22.04) Pip 22_3_1 TOXENV=py37-integration	1h 41m 57s
(ubuntu-22.04) Pip 23_1_2 TOXENV=py37-integration	1h 26m 45s
(macos-12) Pip 20 TOXENV=py311-integration	53m 3s
(ubuntu-22.04) Pip 20 TOXENV=py311-integration	39m 49s
(ubuntu-22.04) Pip 22_3_1 TOXENV=py311-integration	44m 44s
(ubuntu-22.04) Pip 23_1_2 TOXENV=py311-integration	38m 4s
(macos-12) Pip 23_2 TOXENV=py312-integration	1h 3m 50s
(ubuntu-22.04) Pip 23_2 TOXENV=py312-integration	1h 5m 38s
(macos-12) Pip 20 TOXENV=py27	23m 22s
(ubuntu-22.04) Pip 20 TOXENV=py27	11m 33s
(ubuntu-20.04) Pip 20 TOXENV=py35	13m 30s
(PyPy 2.7) Pip 20 TOXENV=pypy27-integration	44m 34s
(PyPy 3.9) Pip 20 TOXENV=pypy39-integration	48m 41s
(PyPy 3.9) Pip 22_3_1 TOXENV=pypy39-integration	1h 13m 30s
(PyPy 3.9) Pip 23_1_2 TOXENV=pypy39-integration	1h 9m 10s
(PyPy 2.7) Pip 20 TOXENV=pypy27	17m 13s
(PyPy 3.9) Pip 20 TOXENV=pypy39	35m 16s
(PyPy 3.9) Pip 22_3_1 TOXENV=pypy39	24m 33s
(PyPy 3.9) Pip 23_1_2 TOXENV=pypy39	30m 9s
Gather Final Status	1s
	18h 8m 22s

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