PHP 8.4 deprecations: Fix implicit nullables

Author: tvdijen

composer.json

@@ -47,7 +47,7 @@
         "simplesamlphp/xml-common": "~1.24.0",
         "simplesamlphp/xml-security": "~1.13.0",
         "simplesamlphp/xml-soap": "~1.7.0",
-        "simplesamlphp/xml-wsdl": "~1.2.0",
+        "simplesamlphp/xml-wsdl": "~1.2.1",
         "simplesamlphp/ws-security": "~1.9.0",
         "symfony/http-foundation": "^6.4"
     },

src/IdP/ADFS.php

@@ -368,7 +368,7 @@ private static function signAssertion(
         string $cert,
         string $algo,
         #[\SensitiveParameter]
-        string $passphrase = null,
+        ?string $passphrase = null,
     ): Assertion {
         $key = PrivateKey::fromFile($key, $passphrase);
         $pubkey = PublicKey::fromFile($cert);