Fix wrong dates shown on table listing

food.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 
 # Copyright 2018 Toni Fadjukoff. All Rights Reserved.
+# Copyright 2019 Google LLC. All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -69,7 +70,7 @@ max_week_daterange = ""
 if max_week >= 1 and max_week <= 52:
   # figure out the date range
   while True:
-    stamp_week = int(time.strftime("%W", time.localtime(stamp)))
+    stamp_week = datetime.datetime.utcfromtimestamp(stamp).isocalendar()[1]
     if stamp_week == max_week:
             break
     stamp += 3600*24