providers/oauth2: improve conformance with client_credentials standard

[BeryJu]

Details

closes #6139

this will not be included in 2024.2 but rather the next release after that

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Checklist

• Local tests pass (ak test authentik/)
• The code has been formatted (make lint-fix)

If an API change has been made

• The API schema has been updated (make gen-build)

If changes to the frontend have been made

• The code has been formatted (make web)

If applicable

• The documentation has been updated
• The documentation has been formatted (make website)

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[github-actions]

authentik PR Installation instructions

Instructions for docker-compose

Add the following block to your .env file:

AUTHENTIK_IMAGE=ghcr.io/goauthentik/dev-server
AUTHENTIK_TAG=gh-providers-oauth2-cc-conform-1707693225-713e22f
AUTHENTIK_OUTPOSTS__CONTAINER_IMAGE_BASE=ghcr.io/goauthentik/dev-%(type)s:gh-%(build_hash)s

For arm64, use these values:

AUTHENTIK_IMAGE=ghcr.io/goauthentik/dev-server
AUTHENTIK_TAG=gh-providers-oauth2-cc-conform-1707693225-713e22f-arm64
AUTHENTIK_OUTPOSTS__CONTAINER_IMAGE_BASE=ghcr.io/goauthentik/dev-%(type)s:gh-%(build_hash)s

Afterwards, run the upgrade commands from the latest release notes.

Instructions for Kubernetes

Add the following block to your values.yml file:

authentik:
    outposts:
        container_image_base: ghcr.io/goauthentik/dev-%(type)s:gh-%(build_hash)s
image:
    repository: ghcr.io/goauthentik/dev-server
    tag: gh-providers-oauth2-cc-conform-1707693225-713e22f

For arm64, use these values:

authentik:
    outposts:
        container_image_base: ghcr.io/goauthentik/dev-%(type)s:gh-%(build_hash)s
image:
    repository: ghcr.io/goauthentik/dev-server
    tag: gh-providers-oauth2-cc-conform-1707693225-713e22f-arm64

Afterwards, run the upgrade commands from the latest release notes.