removed the usage of f-strings to maintain compatibility with python 3.5

django_cryptolock/utils.py

@@ -11,7 +11,9 @@ def verify_signature(address: str, challenge: str, signature: str) -> bool:
     host = settings.MONERO_WALLET_RPC_HOST
     user = settings.MONERO_WALLET_RPC_USER
     pwd = settings.MONERO_WALLET_RPC_PASS
-    wallet_rpc = AuthServiceProxy(f"{protocol}://{user}:{pwd}@{host}/json_rpc")
+    wallet_rpc = AuthServiceProxy(
+        "{}://{}:{}@{}/json_rpc".format(protocol, user, pwd, host)
+    )
 
     result = wallet_rpc.verify(
         {"data": challenge, "address": address, "signature": signature}

tests/test_validators.py

@@ -50,4 +50,4 @@ def test_invalid_address(network, address, settings):
     with pytest.raises(ValidationError) as error:
         validate_monero_address(address)
 
-    assert f"Invalid address for {network}" in str(error.value)
+    assert "Invalid address for {}".format(network) in str(error.value)