temporarily remove the '-Werror' flag for Python 3.15 on Linux (due to _POSIX_C_SOURCE, _XOPEN_SOURCE redefined); skip Intel macOS Python 3.14-15 builds; refactor urllib imports in notebooks

[slayoo]

No description provided.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.89%. Comparing base (11811f0) to head (90fc6ca).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #556   +/-   ##
=======================================
  Coverage   91.89%   91.89%           
=======================================
  Files          56       56           
  Lines        2530     2530           
  Branches      144      144           
=======================================
  Hits         2325     2325           
  Misses        131      131           
  Partials       74       74           

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[slayoo]

The C++ README code problem is unrelated, and should not block PyPI uploads, so merging here, and opening a new isse: #557