fix(psalm): use fully scoped phpseclib3 namespace for instanceof check

The instanceof check was using the unscoped \phpseclib3\Crypt\Common\PrivateKey
but phpseclib is no longer a direct composer dependency on this branch.
Use the scoped OCA\Libresign\Vendor\phpseclib3 prefix to match how the
class is provided via the 3rdparty scoped vendor bundle.

Signed-off-by: Vitor Mattos <1079143+vitormattos@users.noreply.github.com>

Author: vitormattos

lib/Handler/CertificateEngine/AEngineHandler.php

@@ -833,7 +833,7 @@ private function loadCaIssuer(string $configPath): \OCA\Libresign\Vendor\phpsecl
 		$issuer->loadX509($caCert);
 		$caPrivateKey = \OCA\Libresign\Vendor\phpseclib3\Crypt\PublicKeyLoader::load($caKey);
 
-		if (!$caPrivateKey instanceof \phpseclib3\Crypt\Common\PrivateKey) {
+		if (!$caPrivateKey instanceof \OCA\Libresign\Vendor\phpseclib3\Crypt\Common\PrivateKey) {
 			$this->logger->error('Loaded key is not a private key', ['keyType' => get_class($caPrivateKey)]);
 			throw new \RuntimeException('Loaded key is not a private key');
 		}