Starlette-Admin: Unvalidated `order_by` parameter allows ordering by hidden columns (info-exposure oracle) and HTTP 500 DoS

Starlette-Admin is a fast, beautiful and extensible administrative interface framework for FastAPI and Starlette applications. Prior to 0.16.1, the list API does not validate user-supplied order_by and structured where field names against the configured sortable_fields and searchable_fields allowlists. An authenticated user with access to an affected list endpoint can submit arbitrary field names to starlette_admin/base.py and the BaseModelView validation path, bypassing restrictions presented by the administrative user interface. Requests can sort or filter on fields that are not intended to be sortable or searchable, causing limited information exposure. Invalid field names and special Python attribute names such as metadata and the class dunder attribute can also trigger unhandled exceptions and HTTP 500 responses, causing limited denial of service for targeted requests. This issue is fixed in version 0.16.1.