dsa: introduce `serde` #718

Job	Run time
build (thumbv7em-none-eabi, 1.81.0)	20s
test (ubuntu-latest, 1.81.0)	52s
build (thumbv7em-none-eabi, stable)	14s
test (ubuntu-latest, stable)	49s
build (wasm32-unknown-unknown, 1.81.0)	18s
test (macos-latest, 1.81.0)	43s
build (wasm32-unknown-unknown, stable)	11s
test (macos-latest, stable)	44s
test (windows-latest, 1.81.0)	1m 21s
test (windows-latest, stable)	1m 43s
	7m 15s

Provide feedback