Tests

Upgrade to bincode v2 actually released on crates.io #874

Job	Run time
Rustfmt	14s
clippy_check	22s
doc-build	19s
build	3m 23s
test-alloc (ecdsa_fun)	54s
test-alloc (sigma_fun)	49s
test (x86_64-unknown-linux-gnu)	1m 54s
test (armv7-unknown-linux-gnueabihf)	7m 28s
test-alloc (schnorr_fun)	1m 7s
test-alloc (secp256kfun)	52s
test-minimal (schnorr_fun)	56s
test-minimal (secp256kfun)	49s
test-minimal (ecdsa_fun)	51s
test-minimal (sigma_fun)	45s
test-nightly	54s
	21m 37s

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