Update api.py (apache#20711)

(cherry picked from commit 5285f3d)

superset/datasets/api.py

@@ -204,7 +204,7 @@ class DatasetRestApi(BaseSupersetModelRestApi):
         "sql": [DatasetIsNullOrEmptyFilter],
         "id": [DatasetCertifiedFilter],
     }
-    search_columns = ["id", "database", "owners", "sql", "table_name"]
+    search_columns = ["id", "database", "owners", "schema", "sql", "table_name"]
     filter_rel_fields = {"database": [["id", DatabaseFilter, lambda: []]]}
     allowed_rel_fields = {"database", "owners"}
     allowed_distinct_fields = {"schema"}