test: Mark test_resource_management flaky on Windows (#1919)

### Description

`tests/unit/browsers/test_browser_pool.py::test_resource_management`
failed on master CI (Windows, Python 3.10) with
`playwright._impl._errors.Error: Page.goto: net::ERR_NO_BUFFER_SPACE` —
see [run
26453810483](https://github.com/apify/crawlee-python/actions/runs/26453810483/job/77881886837).

The previous fix (#1916) bumped the `goto` timeout to 60s, but the
failure is not a slow response — it's a hard kernel-level socket buffer
exhaustion on Windows when many xdist workers simultaneously launch
Chromium and open sockets. A larger timeout cannot help.

Mark the test with `@pytest.mark.flaky(reruns=3)` to match the existing
project precedent for this exact failure mode (see
`test_stagehand_browser_controller.py` and
`test_adaptive_playwright_crawler.py`).

Author: vdusek

tests/unit/browsers/test_browser_pool.py

@@ -138,6 +138,10 @@ async def test_new_page_with_invalid_plugin() -> None:
             await browser_pool.new_page(browser_plugin=plugin_2)
 
 
+@pytest.mark.flaky(
+    reruns=3,
+    reason='Test is flaky on Windows when Playwright hits net::ERR_NO_BUFFER_SPACE under xdist load.',
+)
 async def test_resource_management(server_url: URL) -> None:
     playwright_plugin = PlaywrightBrowserPlugin(browser_type='chromium')