Add a security policy #118

Job	Run time
package-wheel (manylinux, ubuntu-latest)	20m 30s
package-sdist	6s
package-wheel (macos, macos-latest)	3m 11s
lint	38s
test (ubuntu-latest, 3.7)	3m 22s
package-wheel (win, windows-latest)	4m 31s
test (ubuntu-latest, 3.8)	3m 5s
test (ubuntu-latest, 3.9)	4m 2s
test (ubuntu-latest, 3.10)	2m 41s
test (ubuntu-latest, 3.11)	3m 56s
test (ubuntu-latest, 3.12)	3m 26s
test (macos-latest, 3.7)	8m 34s
test (macos-latest, 3.8)	9m 4s
test (macos-latest, 3.9)	13m 24s
test (macos-latest, 3.10)	9m 28s
test (macos-latest, 3.11)	8m 25s
test (macos-latest, 3.12)	8m 12s
test (windows-latest, 3.7)	10m 57s
test (windows-latest, 3.8)	11m 39s
test (windows-latest, 3.9)	11m 9s
test (windows-latest, 3.10)	11m 8s
test (windows-latest, 3.11)	10m 37s
test (windows-latest, 3.12)	11m 53s
publish	0s
	2h 53m 58s

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