Fix the error code for the ACS view GET

ssoauth/views.py

@@ -152,7 +152,7 @@ class ACSAuthNView(SAMLMixin, View):
     """
 
     def get(self, *args, **kwargs):
-        raise http.Http404()
+        return http.HttpResponse(status=405)
 
     def post(self, request, *args, **kwargs):
         auth = self.get_onelogin_auth(request)