"Example" in api code makes `cryptography` a required dependency

[Dobatymo]

See

c2pa-python/c2pa/c2pa_api/c2pa_api.py

Lines 240 to 257 in 7728124

	# Example of using python crypto to sign data using openssl with Ps256
	from cryptography.hazmat.primitives import hashes, serialization
	from cryptography.hazmat.primitives.asymmetric import padding
	def sign_ps256(data: bytes, key: bytes) -> bytes:
	private_key = serialization.load_pem_private_key(
	key,
	password=None,
	)
	signature = private_key.sign(
	data,
	padding.PSS(
	mgf=padding.MGF1(hashes.SHA256()),
	salt_length=padding.PSS.MAX_LENGTH
	),
	hashes.SHA256()
	)
	return signature

[tmathern]

The cryptography dependency has been removed for prod code.
Note that it is still a dev dependency in v0.12.0, as it is used in tests.