feat(vex): OpenVEX 0.2.0 attestation generator #217

Job	Run time
coverage	10m 48s
test-release	18m 29s
clippy	18s
dispatch-tests	10s
test (ubuntu-latest)	12m 9s
test (windows-latest)	15m 5s
test (macos-latest)	12m 39s
coverage-docker (maven)	4m 30s
coverage-docker (golang)	4m 8s
coverage-docker (cargo)	4m 15s
coverage-docker (gem)	4m 9s
coverage-docker (pypi)	4m 46s
coverage-docker (npm)	4m 20s
e2e-docker (pypi)	4m 3s
e2e-docker (npm)	3m 40s
coverage-docker (deno)	4m 46s
coverage-docker (nuget)	4m 54s
e2e-docker (maven)	3m 48s
e2e-docker (cargo)	3m 39s
e2e-docker (golang)	3m 17s
coverage-docker (composer)	4m 22s
e2e-docker (gem)	3m 30s
e2e-docker (composer)	3m 35s
e2e-docker (deno)	3m 13s
e2e-docker (nuget)	3m 31s
coverage-merge	22s
e2e (ubuntu-latest, e2e_nuget)	29s
e2e (ubuntu-latest, e2e_composer)	29s
e2e (ubuntu-latest, e2e_maven)	26s
e2e (ubuntu-latest, e2e_cargo)	28s
e2e (windows-latest, e2e_safety_cargo_build)	1m 39s
e2e (ubuntu-latest, e2e_safety_cargo_build)	33s
e2e (macos-latest, e2e_safety_cargo_build)	47s
e2e (ubuntu-latest, e2e_golang)	28s
e2e (macos-latest, e2e_safety_pnpm)	46s
e2e (windows-latest, e2e_safety_pnpm)	1m 32s
e2e (ubuntu-latest, e2e_safety_pnpm)	53s
	2h 30m 56s

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