[#6626] Pin Open Klant Client to v0.8.0

[vaszig]

Closes #6626 partly

Changes

• Upgrade Open Klant Client to v0.8.0 (support for verificatieDatum).

Single PR for this upgrade since we are going to gradually/smoothly backport everything needed.

Checklist

Check off the items that are completed or not relevant.

• Impact on features

  • Checked copying a form
  • Checked import/export of a form
  • Config checks in the configuration overview admin page
  • Checked new model fields are usable in the admin
  • Problem detection in the admin email digest is handled

• Dockerfile/scripts

  • Updated the Dockerfile with the necessary scripts from the ./bin folder

• Commit hygiene

  • Commit messages refer to the relevant Github issue
  • Commit messages explain the "why" of change, not the how

• Documentation

  • Added documentation which describes the changes

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.26%. Comparing base (48e673c) to head (a410cbd).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6637   +/-   ##
=======================================
  Coverage   97.26%   97.26%           
=======================================
  Files         859      859           
  Lines       33312    33312           
  Branches     3004     3004           
=======================================
  Hits        32400    32400           
  Misses        603      603           
  Partials      309      309           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[SonnyBA]

The bump in versions does not seem to have any breaking changes, looks good to me 👍

[vaszig]

Backports:

stable/4.0.x: 64ace7c
stable/3.5.x: d2b6627