Add graph of librustzcash crate dependencies to README.md #6458

Job	Run time
Test no-Orchard on Linux	4m 42s
Check ZFuture build on Linux	24s
Check ZFuture build on macOS	39s
Test Orchard on Linux	6m 32s
Check ZFuture build on Windows	3m 17s
Test NU7 on Linux	6m 20s
Test no-Orchard on macOS	5m 44s
Test Orchard on macOS	12m 21s
Test no-Orchard on Windows	9m 28s
Slow Test Orchard on Linux	4m 20s
Latest build on ubuntu-latest	51s
Test Orchard on Windows	12m 57s
Slow Test NU7 on Linux	4m 20s
Build target wasm32-wasi	58s
Latest build on windows-latest	1m 54s
Test NU7 on Windows	13m 47s
Latest build on macOS-latest	1m 5s
Build target thumbv7em-none-eabihf	41s
Bitrot check	1m 15s
Clippy (MSRV)	1m 19s
Clippy (beta)	11s
Code coverage	1h 20m 15s
Intra-doc links	2m 10s
Rustfmt	15s
protobuf consistency	1m 3s
UUID validity	3s
Required status checks have passed	1s
	2h 56m 52s

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