The self-test reads time.clock_gettime_ns(time.CLOCK_MONOTONIC) for
extra_in on even iterations. CPython documents both symbols
"Availability: Unix", so the attribute lookup raises AttributeError on
Windows and python3 reference.py does not run there.
Take extra_in from secrets instead, at a random length, so the self-test
also exercises extra_in of varying length. time has no other use in the
file, so its import goes too.
- An error test vector doesn’t specify the InvalidContributionError type
- In *DeterministicSign*, use GetXonlyPubkey instead of GetPubkey
- The key_agg_and_tweak fn doesn’t specify the return type
- In partial_sig_verify_internal, the pubkey arg should be PlainPk
- Remove unused enumerate() fn calls
- In test_sign_verify, add an additional assert statement
