Raise for status when Yahoo! returns 403

Sometimes Yahoo! returns 403.  This causes a tuple destructuring error later in `parse_response()`, when `.json()` actually does not return anything that can be destructured.

The correct defensive behavior is to fail fast and exit here.

beanprice/sources/yahoo.py

@@ -86,6 +86,7 @@ def get_price_series(ticker: str,
     }
     payload.update(_DEFAULT_PARAMS)
     response = requests.get(url, params=payload, headers={'User-Agent': None})
+    response.raise_for_status()
     result = parse_response(response)
 
     meta = result['meta']
@@ -121,6 +122,7 @@ def get_latest_price(self, ticker: str) -> Optional[source.SourcePrice]:
         }
         payload.update(_DEFAULT_PARAMS)
         response = requests.get(url, params=payload, headers={'User-Agent': None})
+        response.raise_for_status()
         try:
             result = parse_response(response)
         except YahooError as error: