title: Django permission_classes for access to route is not callable
body: <p>I am trying to change the permissions to specific routes. Some routes I want to be open, other routes I want the user to be authenticated. My code is the following:</p>
  
  <pre><code>from rest_framework.decorators import api_view, permission_classes
  from rest_framework.permissions import IsAuthenticated
  from rest_framework.viewsets import GenericViewSet
  
  class UserViewSet(GenericViewSet):
        queryset = User.objects.all()
        serializer_class = UserSerializer
        permission_classes = [IsAuthenticated]
        renderer_classes = [JSONRenderer]
  
  
      @action(url_path="an/api/path", detail=False, methods=["post"], renderer_classes=[JSONRenderer])
      @api_view(['GET'])
      @permission_classes((IsAuthenticated, ))
      def get_stuff(self, request):
          #Will get stuff
  </code></pre>
  
  <p>But I keep getting this error:</p>
  
  <pre><code> File "/code/api/views/UserViewSet.py", line 16, in &lt;module&gt;
  api_1     |     class UserViewSet(GenericViewSet):
  api_1     |   File "/code/api/views/UserViewSet.py", line 33, in UserViewSet
  api_1     |     @permission_classes((IsAuthenticated, ))
  api_1     | TypeError: 'list' object is not callable
  </code></pre>
  
  <p>In my settings.py, I have:</p>
  
  <pre><code>REST_FRAMEWORK = {
      "DEFAULT_PERMISSION_CLASSES": [
          "rest_framework.permissions.IsAuthenticated",
      ],
      "DEFAULT_AUTHENTICATION_CLASSES": [
          "rest_framework_jwt.authentication.JSONWebTokenAuthentication",
          "rest_framework.authentication.SessionAuthentication",
          "rest_framework.authentication.BasicAuthentication",
      ],
      "DEFAULT_RENDERER_CLASSES": (
          "rest_framework.renderers.JSONRenderer",
      )
  </code></pre>
  
  <p>Any idea why it keeps throwing list' object is not callable function?</p>