Use user.is_authenticated as an attribute rockstor#2664

Prior to Django 1.10, user.is_authenticated() was a method.
Since then, compatibility was ensured but this compatibility will be
removed in Django 2.0. This commit thus moves to using the
user.is_authenticated attribute instead.

src/rockstor/storageadmin/views/home.py

@@ -1,5 +1,5 @@
 """
-Copyright (c) 2012-2020 RockStor, Inc. <http://rockstor.com>
+Copyright (c) 2012-2023 RockStor, Inc. <https://rockstor.com>
 This file is part of RockStor.
 
 RockStor is free software; you can redistribute it and/or modify
@@ -13,7 +13,7 @@
 General Public License for more details.
 
 You should have received a copy of the GNU General Public License
-along with this program. If not, see <http://www.gnu.org/licenses/>.
+along with this program. If not, see <https://www.gnu.org/licenses/>.
 """
 
 from django.shortcuts import render
@@ -28,6 +28,7 @@
 
 logger = logging.getLogger(__name__)
 
+
 def login_page(request):
     return render(request, "login.html")
 
@@ -65,7 +66,7 @@ def home(request):
         "update_channel": update_channel,
     }
     logger.debug("context={}".format(context))
-    if request.user.is_authenticated():
+    if request.user.is_authenticated:
         logger.debug("ABOUT TO RENDER INDEX")
         return render(request, "index.html", context)
     else: