stages/prompt: set allow_blank for _read_only fields

[BeryJu]

closes #18228

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[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 92.96%. Comparing base (64965e3) to head (edc6019).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
authentik/stages/prompt/models.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #18297   +/-   ##
=======================================
  Coverage   92.96%   92.96%           
=======================================
  Files         869      869           
  Lines       48143    48144    +1     
=======================================
+ Hits        44756    44759    +3     
+ Misses       3387     3385    -2     

Flag	Coverage Δ
e2e	45.18% <50.00%> (+0.02%)	⬆️
integration	23.17% <50.00%> (+<0.01%)	⬆️
unit	91.07% <50.00%> (+<0.01%)	⬆️
unit-migrate	91.12% <50.00%> (+<0.01%)	⬆️

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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-edc60194f29ea984ff5a2983f753cb5797a0f0cc
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
global:
    image:
        repository: ghcr.io/goauthentik/dev-server
        tag: gh-edc60194f29ea984ff5a2983f753cb5797a0f0cc

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