Custom header triggers error not valid header value

[it-can]

Guzzle version(s) affected: 7.4
PHP version: 8.1.4
cURL version: 7.82.0

Description
I was testing this library (mollie/mollie-api-php#612), which sets a custom header with php_uname(). And my docker returns this value: Linux f0f489981e90 5.10.104-linuxkit #1 SMP Wed Mar 9 19:05:23 UTC 2022 x86_64. This will trigger an error

"Linux f0f489981e90 5.10.104-linuxkit #1 SMP Wed Mar 9 19:05:23 UTC 2022 x86_64" is not valid header value

How to reproduce

<?php
$header = 'Linux f0f489981e90 5.10.104-linuxkit 1 SMP Wed Mar 9 19:05:23 UTC 2022 x86_64';

$client = new \GuzzleHttp\Client();
$response = $client->request('GET', 'https://enswyqyojtxm.x.pipedream.net', [
    'headers' => [
        'User-Agent' => 'testing/1.0',
        'Accept'     => 'application/json',
        'X-Foo'      => ['Bar', 'Baz'],
        'X-TEST'     => $header,
    ]
]);

Possible Solution

Additional context
I tested the whole 7.4 branch but the "problem" seems to be within guzzlehttp/psr7. This line https://github.com/guzzle/psr7/blob/master/src/MessageTrait.php#L262

[it-can]

Problem seems to be with the PSR7 library. Feel free to close this issue...

[GrahamCampbell]

Duplicate of guzzle/psr7#489.