Actually, the code should be the following, for compatibility with both 3.4.x and 4.x:

$config = Configuration::forSymmetricSigner(
    new Sha256(),
    LocalFileReference::file('path/to/integration.private-key.pem')
);

$jwt = $config->builder()
    ->issuedBy($integrationId)
    ->issuedAt(time())
    ->expiresAt(time() + 60)
    ->getToken($config->signer(), $config->signingKey()));

$github->authenticate($jwt, null, Github\Client::AUTH_JWT)

with the following imports at the top:

use Lcobucci\JWT\Configuration;
use Lcobucci\JWT\Signer\Key\LocalFileReference;
use Lcobucci\JWT\Signer\Rsa\Sha256;

in place of the other Lcobucci\JWT imports.

Closing this PR because I don't know why CI is failing (I did update the head branch with the most recent version of the base) and tbh I've lost interest in figuring it out.

@amacrobert-meq Sorry I've lost track of this PR, the failing check can be ignored as it is unrelated. I think the only "action" left here was to implement the sugested changes of @GrahamCampbell or are these already "resolved"? I think these are already applied by you?

So I think we can re-open this PR and have it ready to be merged!

@acrobat Ok, in that case I'm reopening

Thanks @amacrobert-meq! And congrats on your first contribution! 🎉