rfc3339, json, Web5Error, and VerifiableCredential #442

Job	Run time
Build x86_64-unknown-linux-musl target	5m 4s
Build x86_64-unknown-linux-gnu target	3m 1s
Build aarch64-apple-darwin target	2m 20s
Build x86_64-apple-darwin target	5m 12s
lint	1m 8s
rust-test-vectors	3m 25s
test (ubuntu-latest, stable)	1m 26s
test (ubuntu-latest, nightly)	1m 29s
test (macos-latest, stable)	1m 27s
test (macos-latest, nightly)	1m 39s
kotlin-build-test-deploy-snapshot	3m 45s
	29m 56s

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