Add confidence intervals to Forecast model

- add `.low80`, `.high80`, `.low95`, and `.high95` columns
- add check contraints for the confidence intervals
- rename the `.method` column into `.model` for consistency

migrations/env.py

@@ -21,7 +21,11 @@ log_config.fileConfig(context.config.config_file_name)
 
 def include_object(obj, _name, type_, _reflected, _compare_to):
     """Only include the clean schema into --autogenerate migrations."""
-    if type_ in {'table', 'column'} and obj.schema != umd_config.CLEAN_SCHEMA:
+    if (  # noqa:WPS337
+        type_ in {'table', 'column'}
+        and hasattr(obj, 'schema')  # noqa:WPS421 => fix for rare edge case
+        and obj.schema != umd_config.CLEAN_SCHEMA
+    ):
         return False
 
     return True