Add graph of librustzcash crate dependencies to README.md #6468

Job	Run time
Slow Test Orchard on Linux	4m 16s
Test no-Orchard on Linux	4m 37s
Slow Test NU7 on Linux	4m 17s
Test Orchard on Linux	6m 20s
Bitrot check	1m 8s
Test NU7 on Linux	6m 16s
Latest build on ubuntu-latest	50s
Latest build on windows-latest	3m 30s
Latest build on macOS-latest	1m 19s
Build target wasm32-wasi	1m 3s
Build target thumbv7em-none-eabihf	39s
Check ZFuture build on Linux	24s
Test no-Orchard on macOS	6m 50s
Check ZFuture build on macOS	46s
Test Orchard on macOS	10m 40s
Check ZFuture build on Windows	1m 42s
Test no-Orchard on Windows	9m 42s
Test Orchard on Windows	11m 46s
Test NU7 on Windows	12m 9s
Clippy (MSRV)	1m 14s
Clippy (beta)	11s
Intra-doc links	2m 7s
Code coverage	1h 17m 0s
Rustfmt	14s
protobuf consistency	1m 3s
UUID validity	2s
Required status checks have passed	1s
	2h 50m 6s

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