Prepare 20.0.0 release. #1398

Job	Run time
ruff	9s
mypy	31s
sdist	1m 2s
parse_sdl (macos-latest, 3.2.16)	28s
parse_sdl (windows-latest, 3.2.16)	43s
test-docs	2m 21s
tox (ubuntu-latest)	2m 21s
pyodide	2m 48s
build-macos (cp314t-*_universal2)	2m 40s
build-macos (pp310-*)	5m 5s
linux-wheels (x86_64, pp310-manylinux*)	4m 14s
linux-wheels (x86_64, cp314t-manylinux*)	4m 19s
build-macos (cp310-*_universal2)	1m 54s
linux-wheels (aarch64, cp314t-manylinux*)	4m 49s
linux-wheels (aarch64, cp310-manylinux*)	4m 24s
linux-wheels (aarch64, pp310-manylinux*)	3m 40s
linux-wheels (x86_64, cp310-manylinux*)	4m 17s
build (ubuntu-latest, pypy-3.10, x64)	2m 57s
build (windows-11-arm, 3.14t, arm64)	4m 53s
build (windows-latest, 3.14t, x86)	4m 12s
build (ubuntu-latest, 3.14t, x64)	3m 55s
build (windows-latest, pypy-3.10, x64)	3m 45s
build (windows-latest, 3.14t, x64)	3m 43s
build (windows-latest, 3.10, x64)	3m 7s
build (ubuntu-latest, 3.10, x64)	4m 2s
build (windows-latest, 3.10, x86)	3m 28s
build (windows-11-arm, 3.11, arm64)	4m 59s
publish	-1s
	1h 24m 45s

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