idk does this work

index.php

···
     'headers' => [
       'User-Agent' => USER_AGENT_STR,
       'Authorization' => 'Bearer: '.$token->toString()
+    ],
+    'query' => [
+      'client_assertion_type' => 'urn:ietf:params:oauth:client-assertion-type:jwt-bearer',
+      'client_assertion' => $token->toString()
     ]
   ]);
   $provider = new BskyProvider($options, $client, $httpFactory, $httpFactory, $httpFactory);