Enable `curve25519-dalek/serde` (#141) #394

Job	Run time
cargo clippy	23s
Audit	9s
test (--features ristretto255-ciphersuite, --features serde, stable)	1m 19s
test (--features ristretto255-ciphersuite, --features danger, stable)	1m 27s
test (stable)	52s
Taplo	7s
test (--features ristretto255-ciphersuite, stable)	55s
test (--features ristretto255-ciphersuite, --features serde, 1.83.0)	1m 27s
test (--features ristretto255-ciphersuite, --features danger, 1.83.0)	1m 28s
test (--features serde, stable)	1m 14s
test (--features serde, 1.83.0)	1m 22s
test (1.83.0)	58s
Build with no-std on thumbv6m-none-eabi	13s
Build with no-std on thumbv6m-none-eabi	14s
Build with no-std on thumbv6m-none-eabi	12s
Build with no-std on wasm32-unknown-unknown	13s
test (--features ristretto255-ciphersuite, 1.83.0)	59s
test (--features danger, 1.83.0)	1m 18s
Build with no-std on wasm32-unknown-unknown	23s
Build with no-std on wasm32-unknown-unknown	16s
Build with no-std on thumbv6m-none-eabi	22s
Build with no-std on thumbv6m-none-eabi	16s
Build with no-std on wasm32-unknown-unknown	15s
Build with no-std on wasm32-unknown-unknown	15s
test (--features danger, stable)	1m 15s
Build with no-std on thumbv6m-none-eabi	16s
Build with no-std on wasm32-unknown-unknown	21s
cargo fmt	13s
	18m 42s

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