Update satoshisPerByte to float

Author: bobbrodie

src/bitpay/models/invoice/miner_fees_item.py

@@ -15,6 +15,6 @@ class MinerFeesItem(BitPayModel):
     see this support article for more information
     """
 
-    satoshis_per_byte: Union[int, None] = None
+    satoshis_per_byte: Union[float, None] = None
     total_fee: Union[int, None] = None
     fiat_amount: Union[float, None] = None

tests/unit/models/invoice/test_miner_fees_item.py

@@ -6,10 +6,10 @@
 @pytest.mark.unit
 def test_constructor():
     amount = 12.34
-    satoshis = 12345
+    satoshis = 12.345
     total_fee = 4354
     miner_fees_item = MinerFeesItem(fiat_amount=amount, satoshis_per_byte=satoshis, total_fee=total_fee)
 
     assert amount == miner_fees_item.fiat_amount
-    assert 12345 == miner_fees_item.satoshis_per_byte
+    assert 12.345 == miner_fees_item.satoshis_per_byte
     assert total_fee == miner_fees_item.total_fee