Add security.md #3270

Job	Run time
check_release	1m 36s
build (ubuntu-latest, 3.9)	5m 26s
link_check	1m 55s
Make SDist	23s
build (ubuntu-latest, 3.10)	5m 31s
build (ubuntu-latest, 3.11)	5m 16s
test_docs	44s
Test Lint	40s
build (ubuntu-latest, 3.12)	7m 10s
Test Minimum Versions	2m 41s
build (ubuntu-latest, 3.13)	5m 41s
Test Prereleases	2m 24s
build (ubuntu-latest, pypy-3.9)	4m 38s
test_without_debugpy (ubuntu-latest, 3.9)	2m 23s
build (ubuntu-latest, pypy-3.10)	4m 30s
build (windows-latest, 3.9)	7m 3s
build (windows-latest, 3.10)	5m 38s
build (windows-latest, 3.11)	9m 5s
build (windows-latest, 3.12)	4m 41s
build (windows-latest, 3.13)	8m 33s
build (windows-latest, pypy-3.9)	8m 23s
build (windows-latest, pypy-3.10)	8m 37s
build (macos-latest, 3.9)	5m 20s
build (macos-latest, 3.10)	4m 55s
build (macos-latest, 3.11)	4m 35s
build (macos-latest, 3.12)	6m 6s
build (macos-latest, 3.13)	5m 12s
build (macos-latest, pypy-3.9)	3m 58s
build (macos-latest, pypy-3.10)	4m 26s
Install from SDist and Test	2m 33s
coverage	0s
	2h 20m 3s

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