tests

x509, xdsa, xhpke: flesh out certificate handling better #139

Job	Run time
clippy	31s
docs	33s
Test on WASM for wasm32-wasip1	4m 28s
Test on windows-latest	4m 20s
format	8s
Test on macOS-latest	2m 9s
fuzz	2m 2s
Test on WASM for wasm32-unknown-unknown	2m 27s
Test on ubuntu-latest	2m 20s
	18m 58s

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