Enforce that ZIM title must not be longer than 30 chars on our ZIMs

[benoit74]

Rationale

Fix #777

Changes

• add new validation method for ZIM titles (no longer than 30 chars)
• setup this validation method on title metadata on all offliners

Nota : some scraper might not yet properly check for the 30 chars limit, but this is not a valid reason to not block at Zimfarm level to avoid using more than 30 characters.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.34%. Comparing base (2657147) to head (fe905c2).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1024   +/-   ##
=======================================
  Coverage   88.34%   88.34%           
=======================================
  Files          97       97           
  Lines        5414     5415    +1     
=======================================
+ Hits         4783     4784    +1     
  Misses        631      631           

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[rgaudin]

LGTM