Consolidate VS 2017 support from Setuptools #1118

Job	Run time
test (3.8, ubuntu-latest)	40s
test (3.8, macos-latest)	1m 46s
ci_setuptools (3.10, ubuntu-latest)	4m 2s
test_cygwin (39, windows-latest)	4m 25s
test (3.8, windows-latest)	2m 11s
collateral (diffcov)	46s
test (3.12, ubuntu-latest)	1m 8s
collateral (docs)	31s
test_msvc_python_mingw	2m 17s
test_msys2_mingw (mingw64, x86_64, gcc, g++)	1m 40s
test (3.12, macos-latest)	51s
test_msys2_mingw (mingw32, i686, gcc, g++)	2m 21s
test (3.12, windows-latest)	2m 4s
test_msys2_mingw (ucrt64, ucrt-x86_64, gcc, g++)	1m 40s
test (3.9, ubuntu-latest)	52s
test_msys2_mingw (clang64, clang-x86_64, clang, clang++)	1m 46s
test (3.10, ubuntu-latest)	39s
test (3.11, ubuntu-latest)	40s
test (pypy3.10, ubuntu-latest)	2m 14s
check	1s
release	0s
	32m 34s

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