Bump serde from 1.0.217 to 1.0.219 #122

Job	Run time
build	3m 41s
vc_api_test_suites (vc-di-ed25519signature2020-test-suite)	2m 30s
vc_api_test_suites (vc-di-bbs-test-suite)	2m 42s
vc_api_test_suites (vc-bitstring-status-list-test-suite)	2m 30s
	11m 23s

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