Update coverage to 7.15.0 (supersedes #876)

[javihern98]

Summary

Bumps coverage 7.14.3 → 7.15.0 (dev group floor raised to >=7.15.0,<8.0), with the lock regenerated by Poetry itself. This supersedes Dependabot PR #876, which cannot be merged as-is: its machine-generated poetry.lock is invalid.

Why #876 fails CI — the testing (windows-latest, 3.14) job dies with xdist: maximum crashed workers reached. The crash has nothing to do with coverage, pytest-cov, or pytest-xdist:

• Dependabot's lock regeneration dropped the marker-split numpy 2.4.6 entry and stripped the python_version == "3.10" marker from the numpy 2.2.6 entry, collapsing numpy to 2.2.6 for all Python versions — violating the numpy>=2.4.4,<2.5; python_version >= '3.11' constraint introduced in Pin numpy>=2.4.4 for Python >=3.11 so lock regenerations keep cp314 wheels #871. This is the known Dependabot bug dependabot-core#5862 (Poetry multiple-constraint dependencies broken by unrelated updates: only the first lock entry is kept).
• numpy 2.2.6 predates Python 3.14 and ships no cp314 wheels. On windows/3.14 the resulting binary triggers Windows fatal exception: access violation inside numpy._core._multiarray_umath import during collection, killing all 20 xdist workers instantly (node down: Not properly terminated). On ubuntu/macos 3.14 the 2.2.6 binary happens to import, so only the Windows job failed.
• Isolation: the passing cr-881 run (2026-07-09) used the same CPython 3.14.6 on windows with coverage 7.14.3 + numpy 2.4.6; Bump coverage from 7.14.3 to 7.15.0 #876's failing run had coverage 7.15.0 + numpy 2.2.6, and the fault address is in the numpy import.

In this PR the lock diff touches only coverage; both numpy entries survive with their markers intact.

Checklist

• Code quality checks pass (ruff format, ruff check, mypy)
• Tests pass (pytest) — full suite in CI; tests/API smoke run locally with -n auto --cov=vtlengine (239 passed)
• Documentation updated (if applicable) — N/A

Impact / Risk

• Breaking changes? None. Dev-group dependency bump; no runtime dependency or API changes.
• Data/SDMX compatibility concerns? None.
• Notes for release/changelog? Routine dependency maintenance.

Notes

• Bump coverage from 7.14.3 to 7.15.0 #876 should be closed without merging (Dependabot should also auto-close it once this lands, as coverage will no longer be outdated).
• The green windows-3.14 job on this PR is the decisive evidence that coverage 7.15.0 is compatible with the pytest-xdist/pytest-cov stack.
• The Pin numpy>=2.4.4 for Python >=3.11 so lock regenerations keep cp314 wheels #871 constraint alone does not protect us from dependabot-core#5862 — Dependabot writes a lock that violates pyproject.toml markers, and poetry install trusts the lock. Any future Dependabot PR here needs its lock diff checked for the numpy entries (or a CI guard added; happy to file a follow-up Task for that).
• No associated issue, so no closing keyword.