Update error message in current_stock_price.py

Author: cclauss

web_programming/current_stock_price.py

@@ -23,7 +23,7 @@
 def stock_price(symbol: str = "AAPL") -> str:
     """
     >>> stock_price("EEEE")
-    '- '
+    'No <fin-streamer> tag with the specified data-testid attribute found.'
     >>> isinstance(float(stock_price("GOOG")),float)
     True
     """