Merge pull request #456 from zcash/bump-zcash_spec #3368

Job	Run time
Latest build on ubuntu-latest	1m 6s
Build target wasm32-wasi	31s
Latest build on windows-latest	1m 50s
Test on ubuntu-latest	8m 59s
Build target thumbv7em-none-eabihf	33s
Latest build on macOS-latest	52s
Test on windows-latest	9m 50s
Test on macOS-latest	7m 39s
Bitrot check	1m 10s
Book tests	15s
Code coverage	7m 13s
Intra-doc links	1m 27s
Rustfmt	15s
	41m 40s

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