Fix warnings during test execution

[imdshr]

Summary

When running command uv run pytest ConfigurationDeskMCP/tests warning was raised.

=========================================== warnings summary ===========================================
tests/test_runtime_guards.py::test_preconditions_propagate_bridge_errors
tests/test_runtime_guards.py::test_preconditions_report_unexpected_probe_failures
  D:\Repos\ConfigurationDeskBusManagerMCP\ConfigurationDeskMCP\sources\server\preconditions.py:222: DeprecationWarning: 'asyncio.iscoroutinefunction' is deprecated and slated for removal in Python 3.16; use inspect.iscoroutinefunction() instead
    if asyncio.iscoroutinefunction(check_fn):

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html

Proposed changes address warning cause.

Validation

• uv run ruff check .
• uv run ruff format --check .
• uv run pytest ConfigurationDeskMCP/tests
• uv run configurationdesk-mcp --list-tools
• Documentation and tool specifications are updated when applicable.
• No credentials, local paths, proprietary assets, or generated artifacts were added.