problem with PrivateKeyTestnet

[julien92-cyber]

Hi !

first at all, thank you for your work, it is very appreciated :))

It seems there is movement on testnet (testnet3 => testnet4) because the package didn't work anymore on testnet address

key = PrivateKeyTestnet()
utxos = key.get_unspents()

throw an error whereas

key = Key()
utxos = key.get_unspents()

send empty list

Error is linked to API call to testnet unspend :

NetworkAPI.get_unspent_testnet(self.address)
return api_call(address)
response = r.json()
requests.exceptions.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

thank in advance for your help :)

edit : BTW sending trx in testnet seem not working too (#197)