Fix typo (#565)

Author: brpauwels

lib/Gitlab/Client.php

@@ -465,7 +465,7 @@ public function authenticate($token, $authMethod = null, $sudo = null)
             @trigger_error(sprintf('The $authMethod will become required in version 10.0. Not providing an explicit authentication method is deprecated since version 9.18.'), E_USER_DEPRECATED);
             $authMethod = self::AUTH_URL_TOKEN;
         } elseif (self::AUTH_URL_TOKEN === $authMethod) {
-            @trigger_error(sprintf('The AUTH_URL_TOKEN authentivation method is deprecated since version 9.18 and will be removed in 10.0. Use AUTH_HTTP_TOKEN instead.'), E_USER_DEPRECATED);
+            @trigger_error(sprintf('The AUTH_URL_TOKEN authentication method is deprecated since version 9.18 and will be removed in 10.0. Use AUTH_HTTP_TOKEN instead.'), E_USER_DEPRECATED);
         } elseif (self::AUTH_HTTP_TOKEN !== $authMethod && self::AUTH_OAUTH_TOKEN !== $authMethod) {
             @trigger_error(sprintf('Passing an invalid authentication method is deprecated since version 9.1 and will be banned in version 10.0.'), E_USER_DEPRECATED);
         }