Fix metadata for PostContent

[wfehr]

These changes provide 3 things:

1. fix test-runner for updated svglib-version -> Install issue deeplook/svglib#413
   • edit: also added the system dependency for the migration test workflow
   • the version 1.6.0 introduced a new system dependency which will now be installed in the tests
   • another solution if test-runtime is too long with that: pin svglig<1.6.0 for tests
2. fix metadata for PostContent
   • the old djangocms-blog had translatable models for category and post
   • the new stories (and cms > 4) models now switched into: category = translatable, post => post + post-content
   • PostContent has the ModelMeta-Mixin => Post does not - the _metadata-attribute still remained in Post instead of PostContent
3. added [og|schemaorg|twitter]_title-attributes for Category/PostContent in _metadata and added checks in tests for that
4. edit: fixes usage for meta.tag (PostContent) and meta.locale (PostContent + PostCategory)

Tests are running successfully with these changes: https://github.com/wfehr/djangocms-stories/actions/runs/18707460615

[codecov]

Codecov Report

❌ Patch coverage is 48.78049% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.00%. Comparing base (bc4bb04) to head (00308ab).

Files with missing lines	Patch %	Lines
djangocms_stories/models.py	48.78%	15 Missing and 6 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #48      +/-   ##
==========================================
- Coverage   86.67%   86.00%   -0.67%     
==========================================
  Files          23       23              
  Lines        2071     2108      +37     
  Branches      230      239       +9     
==========================================
+ Hits         1795     1813      +18     
- Misses        183      196      +13     
- Partials       93       99       +6     

☔ View full report in Codecov by Sentry.
📢 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.

[wfehr]

I can of course also provide different PRs if needed - since the changes provided are 2 separate fixes and 1 (little) feature.

[wfehr]

Added another 2 fixes for meta.tag and meta.locale.

[fsbraun]

@wfehr Thanks so much! Great work!

Can I ask you a few things:

• Can you please remove the Cairo change - elsewhere I have added svglib!=1.6.0 to the test setup ?
• Can you undo the changes in the djangocms_blog folder - it is only needed for migration purposes.
• If at all possible, I would appreciate some basic tests for the new PostContent methods...