Merge pull request #238 from alma/fix/headers

fix: errors in header

Author: Francois-Gomis

src/Client/Application/Endpoint/AbstractEndpoint.php

@@ -35,7 +35,7 @@ public function __construct(ClientInterface $client)
     private function createRequest(string $method, string $uri, array $body = []): Request {
 
         $headers = [
-            'User-Agent' => $this->client->getConfig()->getUserAgentString(),
+            'User-Agent' => [$this->client->getConfig()->getUserAgentString()],
             'Authorization' => ['Alma-Auth ' . $this->client->getConfig()->getApiKey()]
         ];
         return new Request($method, $uri, $headers, json_encode($body));