ci: Prepare release of djangocms-text-ckeditor 5.1.5

[fsbraun]

What's Changed Since Last Release

• fix(settings): Extend ALLOW_TOKEN_PARSERS if custom one is provided by @DmytroLitvinov in https://github.com/django-cms/djangocms-text-ckeditor/pull/654
• Remove Flash plugin in the default settings by @MacLake in https://github.com/django-cms/djangocms-text-ckeditor/pull/656
• fix: Allow for request-free context objects for testing purposes by @fsbraun in https://github.com/django-cms/djangocms-text-ckeditor/pull/659
• Support djangocms-picture 2.0.0 and higher in create_picture_plugin by @leture in https://github.com/django-cms/djangocms-text-ckeditor/pull/660
• Update test matrix to include Django 5 by @protoroto in https://github.com/django-cms/djangocms-text-ckeditor/pull/662

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (05f9b27) 81.79% compared to head (00fe405) 81.79%. Report is 1 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #664 +/- ## ======================================= Coverage 81.79% 81.79% ======================================= Files 20 20 Lines 912 912 Branches 122 122 ======================================= Hits 746 746 Misses 138 138 Partials 28 28 ```

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