Add graph of librustzcash crate dependencies to README.md #6460

Job	Run time
Latest build on ubuntu-latest	1m 6s
Latest build on windows-latest	2m 37s
Latest build on macOS-latest	1m 27s
Check ZFuture build on Linux	24s
Check ZFuture build on macOS	46s
Test no-Orchard on Linux	4m 25s
Check ZFuture build on Windows	2m 25s
Test Orchard on Linux	6m 24s
Test no-Orchard on macOS	6m 59s
Test NU7 on Linux	6m 30s
Slow Test Orchard on Linux	4m 15s
Test Orchard on macOS	9m 25s
Slow Test NU7 on Linux	4m 17s
Test no-Orchard on Windows	9m 57s
Test Orchard on Windows	11m 59s
Bitrot check	1m 9s
Test NU7 on Windows	13m 11s
Build target wasm32-wasi	57s
Build target thumbv7em-none-eabihf	39s
Clippy (MSRV)	1m 14s
Clippy (beta)	14s
Code coverage	1h 22m 57s
Intra-doc links	2m 10s
Rustfmt	14s
protobuf consistency	1m 2s
UUID validity	4s
Required status checks have passed	1s
	2h 56m 48s

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