Deny unknown fields (#272) (#351) #775

Job	Run time
lint	11s
integration-test	2m 44s
unit-test	35s
print-pack-getting-started-output (aarch64-unknown-linux-musl)	6m 26s
print-pack-getting-started-output (x86_64-unknown-linux-musl)	3m 39s
	13m 35s

Provide feedback