sources/oauth: fix OAuth Client sending token request incorrectly

[BeryJu]

closes #9289

Details

REPLACE ME

---

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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✅ Deploy Preview for authentik-storybook canceled.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.40%. Comparing base (853239d) to head (85558a4).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9474      +/-   ##
==========================================
- Coverage   92.41%   92.40%   -0.02%     
==========================================
  Files         668      668              
  Lines       32667    32667              
==========================================
- Hits        30190    30186       -4     
- Misses       2477     2481       +4     

Flag	Coverage Δ
e2e	50.67% <100.00%> (+<0.01%)	⬆️
integration	26.02% <0.00%> (ø)
unit	89.69% <0.00%> (ø)

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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-ghcr.io/goauthentik/dev-server:gh-85558a4065de54d2478758a76c7c02178cf6d70f
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-ghcr.io/goauthentik/dev-server:gh-85558a4065de54d2478758a76c7c02178cf6d70f-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-ghcr.io/goauthentik/dev-server:gh-85558a4065de54d2478758a76c7c02178cf6d70f

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-ghcr.io/goauthentik/dev-server:gh-85558a4065de54d2478758a76c7c02178cf6d70f-arm64

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

[BeryJu]

/cherry-pick version-2024.4