Update composer.json

Fixed php Fatal error
```
PHP Fatal error:  Declaration of FOS\OAuthServerBundle\Storage\OAuthStorage::checkGrantExtension() must be compatible with OAuth2\IOAuth2GrantExtension::checkGrantExtension(OAuth2\IOAuth2Client $client, $uri, array $inputData, array $authHeaders) in /var/web/Accounts2/vendor/friendsofsymfony/oauth-server-bundle/FOS/OAuthServerBundle/Storage/OAuthStorage.php on line 33
```