feat: add milestone management workflow #139

Job	Run time
Release Validation / check-paths	7s
Release Validation / build-artifacts	4m 4s
Release Validation / install-and-smoke (3.12)	55s
Release Validation / install-and-smoke (3.11)	51s
Release Validation / install-and-smoke (3.10)	45s
Release Validation / summary	3s
	6m 45s

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