fix: convert set to list

Author: alukach

stac_fastapi/pgstac/core.py

@@ -617,7 +617,7 @@ def _clean_search_args(  # noqa: C901
                 else:
                     includes.add(field)
 
-            base_args["fields"] = {"include": includes, "exclude": excludes}
+            base_args["fields"] = {"include": list(includes), "exclude": list(excludes)}
 
         if q:
             base_args["q"] = q