Open WebUI: Users denied by the OAuth role policy can still sign in via token exchange

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.8.0 until 0.11.1, Open WebUI's OAuth token exchange endpoint issues a session for a provider access token without running the OAuth role management that the normal OAuth login callback runs. A user whose provider roles the login callback would refuse, or would demote, could still obtain a working session at their existing role through this endpoint. This issue is fixed in version 0.11.1.