Fix crash on Python 3.12+

[abizer]

Summary

Fixes issue where structured exception logging via stackprinter crashes on Python 3.12+ for certain tracebacks with `AssertionError` at `source_inspection.py:62` (and downstream `TypeError: '<=' not supported between instances of 'int' and 'NoneType'` in consumers like Loguru).

Root cause

Since CPython 3.12, `tb.tb_lineno` and `frame.f_lineno` can return `None` when the instruction at `tb_lasti` / `f_lasti` has no line mapping — e.g. synthetic RESUME/CACHE opcodes or certain async-suspension edge cases. `extraction.get_info` passed that `None` straight through to `source_inspection.annotate`, which blew up on `assert isinstance(lineno, int)`. In 3.11 `tb_lineno` was a plain `T_INT` PyMemberDef so the None path never existed — which is why the upstream maintainer is seeing it as a 3.14 regression even though the underlying CPython change landed in 3.12.

Confirmed by reading `Python/traceback.c`'s `tb_lineno_get` at the v3.14.2 tag (`Py_RETURN_NONE` when `PyCode_Addr2Line(code, lasti) < 0`), and reproduced locally with a synthetic `types.TracebackType(None, frame, 1<<20, -1)` that triggers the exact crash from production.

Changes

1. `extraction.get_info` — after reading `tb.tb_lineno` or `frame.f_lineno`, fall back to `frame.f_code.co_firstlineno` when the value is `None`, so the frame still renders with the function header highlighted instead of crashing downstream formatters.
2. Regression test — `test_tb_with_none_lineno` constructs a synthetic traceback with an out-of-range `tb_lasti` so `tb.tb_lineno` returns `None`, then formats through `stackprinter.format()` end-to-end. Skips on interpreters where the getter doesn't return `None`.
3. Release 0.2.13 — `setup.py` version bump + CHANGELOG entry.
4. CI matrix — Python 3.13 and 3.14 added to the build matrix so future regressions in this area get caught upstream instead of only in downstream consumers. Also adds a minimal `.gitignore` covering `pycache`, `.egg-info`, `build/`, `dist/`, `.venv`, and `.pytest_cache`.

Test plan

• `pytest tests/` passes on Python 3.11, 3.12, and 3.14 (8/8 including the new regression test)
• Reproducer for ARE-2675 now renders a formatted frame instead of crashing with `AssertionError`
• Existing demos (`demo.py`, `demo_chained_exceptions.py`, `demo_logging.py`) still produce expected output on 3.14

🤖 Generated with Claude Code