[BUG] Can't run tests with multiple browsers when overriding page fixture

Context:

• Playwright Version: 1.34.0 (pytest-playwright: 0.3.3)
• Operating System: Linux
• Python version: 3.11
• Browser: All

Code Snippet

Just a simple test that overrides the page fixture.

import pytest


@pytest.fixture
def page(page):
    # do something with the page
    yield page


def test(page):
    assert True

Describe the bug

When running the above test file with pytest --browser firefox --browser chromium only one instance of the test is run and the following warning is given out instead:

pytest_playwright/pytest_playwright.py:326: UserWarning: When using unittest.TestCase specifying multiple browsers is not supported

When I include some other playwright fixture in either the page fixture or the test method, the test is run with the specified browsers as expected.

So for example, this works:

def test(page, browser_name):  # another playwright fixture
    assert True

But this does not:

def test(page, monkeypatch):  # a pytest fixture
    assert True

Reproduce the issue with pytest --browser firefox --browser chromium using the overriding page fixture, then inspect pytest_playwright/pytest_playwright.py around line 326. Compare the fixture-only case with a test that includes browser_name and verify that the overridden page fixture runs once per requested browser without the unittest.TestCase warning.