balloon-hash: bump `crypto-bigint` to v0.6.0-rc.7; MSRV 1.83 (#549) #1010

Job	Run time
minimal-versions	0s
build (1.81.0, thumbv7em-none-eabi)	17s
test (1.81.0)	21s
build (1.81.0, wasm32-unknown-unknown)	16s
test (stable)	19s
build (stable, thumbv7em-none-eabi)	21s
build (stable, wasm32-unknown-unknown)	20s
	1m 54s

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