Use form_end instead of closing HTML tag by hand (#617)

* Now properly closing authorization form

Now using `form_end` instead of closing directly the HTML tag.

* Removed extraneous form_rest call

The form_end function already calls form_rest.
See https://symfony.com/doc/current/form/form_customization.html#form-end-form-view-variables for more informations.

Resources/views/Authorize/authorize_content.html.twig

@@ -7,5 +7,4 @@
     {{ form_row(form.redirect_uri) }}
     {{ form_row(form.state) }}
     {{ form_row(form.scope) }}
-    {{ form_rest(form) }}
-</form>
+{{ form_end(form) }}