Impl `serde` for `DynamicColor` #234

# to view logs

Job	Run time
formatting	21s
cargo test (windows-latest)	31s
cargo check (msrv) (wasm32)	20s
cargo test (macos-latest)	27s
cargo clippy (windows-latest)	49s
cargo check (msrv) (windows-latest)	36s
cargo test (ubuntu-latest)	14s
cargo clippy (macos-latest)	33s
cargo check (msrv) (macos-latest)	21s
cargo clippy (ubuntu-latest)	33s
cargo clippy (wasm32)	27s
cargo check (msrv) (ubuntu-latest)	16s
cargo doc	22s
typos	3s
cargo test (wasm32)	13s
	6m 6s

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