faulthandler: register faulthandler_timeout as type=float

[artem-sitd]

Fix #15132.

Problem

faulthandler_timeout was registered without a type, so it defaulted to string. In TOML configuration (pytest.toml / pyproject.toml) a native number — the documented and example form — was rejected:

ERROR: pytest.toml: config option 'faulthandler_timeout' expects a string, got int: 5

Change

Register faulthandler_timeout with type="float" (src/_pytest/faulthandler.py), matching its documented :type: and the float coercion already done in the faulthandler plugin. This is consistent with the other typed options (bool, int, float), all of which reject strings in TOML mode.

INI string values keep working (coerced str -> float in _getini_ini), so faulthandler_timeout = 5 in an .ini file is unchanged behaviour.

Tests

Added test_timeout_accepts_native_toml_numbers in testing/test_faulthandler.py; full test_faulthandler.py and TestConfigAPI pass.

Changelog fragment added as changelog/15132.bugfix.rst.

[The-Compiler]

Duplicate of #15133 (and also unnecessarily beckwards incompatible for toml)