Investigate what's up with certain tests

When running in --testdox mode, the test output shows the following tests with a warning sign, but no test failure/warnings/notices/skips/incompletes.

We should figure out why these tests show a ⚠️ sign, and, if relevant, see if the PHPUnit docs/output about this should be improved.

Curl (WpOrg\Requests\Tests\Transport\Curl\Curl)
 ⚠ Stream to non writable file
 ⚠ Stream to invalid file

Fsockopen (WpOrg\Requests\Tests\Transport\Fsockopen\Fsockopen)
 ⚠ Stream to non writable file
 ⚠ Stream to invalid file

Decompression (WpOrg\Requests\Tests\Requests\Decompression)
 ⚠ Decompress with deflate:·foobar
 ⚠ Decompress with deflate:·Requests·for·PHP
 ⚠ Decompress with deflate·without·zlib·headers:·foobar
 ⚠ Decompress with deflate·without·zlib·headers:·Requests·for·PHP
 ⚠ Decompress with deflate·without·zlib·headers:·compression·level·1
 ⚠ Decompress with deflate·without·zlib·headers:·compression·level·3
 ⚠ Decompress with deflate·without·zlib·headers:·compression·level·9
 ⚠ Compatible inflate with not·compressed:·Requests·for·PHP
 ⚠ Compatible inflate with deflate:·foobar
 ⚠ Compatible inflate with deflate:·Requests·for·PHP
 ⚠ Compatible inflate with deflate·without·zlib·headers:·foobar
 ⚠ Compatible inflate with deflate·without·zlib·headers:·Requests·for·PHP
 ⚠ Compatible inflate with deflate·without·zlib·headers:·compression·level·1
 ⚠ Compatible inflate with deflate·without·zlib·headers:·compression·level·3
 ⚠ Compatible inflate with deflate·without·zlib·headers:·compression·level·9

Found in: https://github.com/WordPress/Requests/actions/runs/10666014665/job/29560590885

Reproduce the output in the linked GitHub Actions run using --testdox, focusing on the Curl, Fsockopen, and Decompression tests listed in the issue. Inspect how PHPUnit classifies and renders these warning signs, then determine whether the behavior or the documentation/output needs changing. Done means the warning signs have an explained and verified outcome.