`PytestCollectionWarning` (and any other warnings) should be treated as an error in strict mode

What's the problem this feature will solve?

when i enable the new strict mode in pytest settings, i expect any warnings to become errors. but there seems to still be some warnings where this isn't the case:

# pyproject.toml

[tool.pytest]
strict = true

# tests/test_foo.py

class TestFoo:
    def __new__(cls): ...

$ pytest --collectonly
===================================================================================== test session starts ======================================================================================
platform linux -- Python 3.14.0, pytest-8.4.2, pluggy-1.6.0
rootdir: /home/me/projects/test
configfile: pyproject.toml
collected 0 items                                                                                                                                                                              

======================================================================================= warnings summary =======================================================================================
tests/test_foo.py:3
  /home/me/projects/test/tests/test_foo.py:3: PytestCollectionWarning: cannot collect test class 'TestFoo' because it has a __new__ constructor (from: tests/test_foo.py)
    class TestFoo:

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
================================================================================= no tests collected in 0.01s ==================================================================================

Describe the solution you'd like

strict mode should make all pytest warnings an error by default

Alternative Solutions

configuring them as described here, but it would be much more convenient if i could enable all of pytest's strictness with a single setting.

Reproduce the behavior with the shown pyproject.toml setting and tests/test_foo.py example, running pytest --collectonly. Trace how strict mode handles pytest warnings and compare that with the documented warning configuration. Done means strict mode treats PytestCollectionWarning and other pytest warnings as errors by default, with coverage for the reported case.