style: format code with Black and isort

This commit fixes the style issues introduced in d5b9f53 according to the output
from Black and isort.

Details: None

firstrade/order.py

@@ -104,7 +104,7 @@ def place_order(
             raise ValueError("AON orders must be a limit order.")
         if order_instruction == OrderInstructions.AON and quantity <= 100:
             raise ValueError("AON orders must be greater than 100 shares.")
-            
+
         data = {
             "submiturl": "/cgi-bin/orderbar",
             "orderbar_clordid": "",