…) in sanitizer runs

Under ASan/LSan with Python 3.12 on Ubuntu 22.04/24.04, the cleanup tests
report direct leaks rooted in CPython’s unicode interning path (frames via
PyUnicode_New) during module import in our embedded init.

This is a known CPython issue (python/cpython#113190). Interned-unicode
cleanup was re-enabled in 3.13 (python/cpython#113601) but not backported
to 3.12. To keep CI signal meaningful while we still test against 3.12,
enable a narrow LSan suppression for PyUnicode_New only, and only on 3.12.

Notes:
- detect_leaks=1 remains enabled; the suppression is limited to PyUnicode_New
  and won’t mask leaks in PythonQt.
- Remove once CI moves off Python 3.12.

Refs: python/cpython#113190, python/cpython#113601

…) in sanitizer runs

Under ASan/LSan with Python 3.12 on Ubuntu 22.04/24.04, the cleanup tests
report direct leaks rooted in CPython’s unicode interning path (frames via
PyUnicode_New) during module import in our embedded init.

This is a known CPython issue (python/cpython#113190). Interned-unicode
cleanup was re-enabled in 3.13 (python/cpython#113601) but not backported
to 3.12. To keep CI signal meaningful while we still test against 3.12,
enable a narrow LSan suppression for PyUnicode_New only, and only on 3.12.

Notes:
- detect_leaks=1 remains enabled; the suppression is limited to PyUnicode_New
  and won’t mask leaks in PythonQt.
- Remove once CI moves off Python 3.12.

Refs: python/cpython#113190, python/cpython#113601