Release blobby v0.4.0 #1902

Job	Run time
build (1.85.0, thumbv7em-none-eabi)	15s
test (1.85.0)	13s
build (stable, wasm32-unknown-unknown)	13s
test (stable)	19s
build (1.85.0, wasm32-unknown-unknown)	18s
build (stable, thumbv7em-none-eabi)	10s
minimal-versions / minimal-versions	27s
	1m 55s

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