chore: align dev dependencies, CI and tooling with saic-ismart-client-ng

[nanomad]

Brings the gateway in line with the housekeeping done in the client library.

• Dev dependencies: ruff 0.17.1, mypy 2.4, coverage 7.16, pytest-cov, pytest-asyncio, pytest-mock, pylint 4.1 and pre-commit 4.7. The lock file is refreshed.
• Ruff 0.17: ignore the new CPY001 and ICN001 rules (as the library does) and PLR0917, the positional-arguments twin of the already ignored PLR0913. Fix two RUF036 findings, and use LOG.error(..., exc_info=...) instead of LOG.exception where there is no active exception (same output). Remove the unused gmqtt mypy override left from the aiomqtt migration.
• CI: actions/checkout v7, actions/setup-python v7 and actions/cache v6. The venv cache key now includes the Python version.
• Pre-commit: poetry 2.5.1, ruff v0.17.1 and pre-commit-hooks v6.0.0.
• Dependabot: weekly updates for GitHub Actions, pip (dev dependencies grouped) and Docker.

Ruff, mypy and the full test suite pass locally (318 tests). pre-commit run --all-files could not be run locally because the hook environments need Python 3.13, so the CI run is the first check of the workflow changes.