Handle missing results field from FR

The Federal Register API used to return `results: []` when there were no results, but now it just doesn't include the `results` key at all. This handles the change.

rule_scout.py

@@ -134,7 +134,7 @@ def get_recent_proposed_rules(self, from_date: date | None = None, to_date: date
         }
         while next_options:
             page = self.get(**next_options).raise_for_status().json()
-            yield from page['results']
+            yield from page.get('results') or []
 
             next_url = page.get('next_page_url')
             next_options = {'url': next_url} if next_url else None