chore: use `coins-ledger` from crates.io #1391

Job	Run time
no-std build	43s
WASM tests	3m 56s
Unix tests (ubuntu-latest, stable)	5m 44s
Unix tests (ubuntu-latest, nightly)	6m 51s
Unix tests (macos-12, stable)	6m 52s
Unix tests (macos-12, nightly)	8m 2s
Windows tests (stable, x86_64-pc-windows-gnu)	5m 47s
Windows tests (stable, x86_64-pc-windows-msvc)	7m 22s
Windows tests (nightly, x86_64-pc-windows-gnu)	6m 14s
Windows tests (nightly, x86_64-pc-windows-msvc)	7m 25s
	58m 56s

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