Merge pull request #402 from zcash/ci-updates #3044

Job	Run time
Build target wasm32-wasi	4m 24s
Latest build on ubuntu-latest	48s
Book tests	12s
Latest build on windows-latest	2m 7s
Bitrot check	5m 0s
Latest build on macOS-latest	1m 18s
Code coverage	12m 20s
Test on ubuntu-latest	11m 3s
Intra-doc links	5m 12s
Test on windows-latest	12m 17s
Test on macOS-latest	11m 17s
Rustfmt	13s
	1h 6m 11s

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