Make warning more verbose

esap_client/shopping_client.py

@@ -98,7 +98,7 @@ class ShoppingClient:
                     "shopping_cart"
                 ]
             else:
-                warn(f"Unable to load data from {self.host}; is your key valid?")
+                warn(f"Unable to load data from {self.host}; check your token for expiry, scopes and audience. Please ask your ESAP administrator for more info.")
 
         if filter_archives:
             self.basket = self._filter_on_archive()