Enable `fast` feature of ed25519-dalek (#190) #200

Job	Run time
Test Suite (stable)	6m 28s
Builds (ubuntu-22.04, aarch64-linux-android)	1m 38s
Bench	0s
Test Suite (beta)	6m 40s
Builds (ubuntu-22.04, x86_64-unknown-linux-musl)	1m 31s
Rustfmt	2m 45s
Test Suite (1.70.0)	7m 17s
Builds (ubuntu-22.04, wasm32-unknown-unknown, --features wasm --no-default-features)	3m 31s
Builds (macos-13, aarch64-apple-ios)	4m 20s
Builds (macos-13, x86_64-apple-darwin)	2m 41s
Builds (macos-14, aarch64-apple-darwin)	3m 31s
Builds (windows-2019, x86_64-pc-windows-msvc)	4m 59s
Upload benchmark results	0s
	45m 21s

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