fixed ecdsa_verify assertion failure

[duckki]

Summary:

• Happens when the message is not an address.
• It's supposed to check if the message is an address, not the public key.
• Also, fixed bugs in get_version_byte and ecdsa_verify_addr.

Reproducer:

from cryptos import (sha256, Bitcoin, ecdsa_sign)

priv = sha256('some big long brainwallet password')
print("priv:", priv)

chain = Bitcoin()

# take 1
message = "Hello, world!"
signature = ecdsa_sign(message, priv, chain)
print("signature:", signature)

# take 2
signature = ecdsa_sign("", priv, chain)
print("signature:", signature)

# take 3
addr = chain.privtoaddr(priv)
signature = ecdsa_sign(addr, priv, chain)
print("signature:", signature)