OAuth2 require DB strong consistancy

[lsjostro]

Describe the bug
When using PG read replicas with async replication you will run into a race condition.
Exactly here will require strong consistency https://github.com/goauthentik/authentik/blob/main/authentik/providers/oauth2/views/token.py#L219. Might be more places also?

Either document that Authentik to require strong consistency or force certain DB calls to primary db instance?

To Reproduce
Steps to reproduce the behavior:

1. Create a oidc provider as Public (PKCE).
2. Have a PG cluster with async replication and configure Authentik with read replicas.
3. Try auth.

Expected behavior
successful auth

Logs
Server: {.. "event": "Code does not exist", ..}
Client: invalid_grant

Version and Deployment (please complete the following information):

• authentik version: 2024.8.1