Merge pull request #449 from zcash/pczt-improvements #3323

Job	Run time
Bitrot check	2m 12s
Book tests	13s
Latest build on ubuntu-latest	46s
Build target wasm32-wasi	1m 30s
Latest build on windows-latest	2m 56s
Code coverage	9m 7s
Latest build on macOS-latest	52s
Intra-doc links	2m 18s
Rustfmt	17s
Test on ubuntu-latest	10m 13s
Test on windows-latest	12m 4s
Test on macOS-latest	9m 11s
	51m 39s

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