ES256 is used as "alg" in JWT generation regardless of actual ECC certificate curve

[Caligatio]

Describe the bug
Regardless of the curve used in an ECC certificate, Authentik sets the "alg" in the JWT to ES256. ES256 is explicitly defined as using the P-256 curve so this causes problem for certificates using P-384 or P-521.

To Reproduce
Steps to reproduce the behavior:

1. Load a ECC P-384 or P-521 cert into Authentik
2. Create a OAUth2/OpenID provider and select the above ECC cert as the "Signing Key"
3. Experience validation errors from a well-behaved JWT validation library (e.g. authlib)

Expected behavior
A valid OIDC JWT to be issued while using a P-384 or P-521 signing key

Screenshots
N/A

Logs
N/A

Version and Deployment (please complete the following information):

• authentik version: 2024.8.3
• Deployment: docker-compose