Tests

Upgrade to bincode v2 actually released on crates.io #876

Job	Run time
Rustfmt	14s
test (armv7-unknown-linux-gnueabihf)	7m 23s
clippy_check	35s
build	48s
test (x86_64-unknown-linux-gnu)	1m 57s
doc-build	30s
test-alloc (secp256kfun)	47s
test-alloc (ecdsa_fun)	52s
test-nightly	1m 38s
test-alloc (sigma_fun)	46s
test-alloc (schnorr_fun)	1m 2s
test-minimal (sigma_fun)	52s
test-minimal (schnorr_fun)	56s
test-minimal (secp256kfun)	54s
test-minimal (ecdsa_fun)	55s
	20m 9s

Provide feedback