Calendar navigation bug

[alucardthefish]

Describe the bug

The month navigation of the calendar fails when you try to pass to another year. For example, if you are in month: december, year: 2020 and try to go to next month or from january 2020 to december 2019 through previous month.

To Reproduce

Steps to reproduce the behavior:

1. Go to http://127.0.0.1:8000/calendar/2020/12
2. Click on 'Next month' link
3. See error in the screenshot below

Expected behavior

The expected behavior is to display the days in the calendar corresponding to january 2021

Screenshots

Desktop (please complete the following information):

• OS: [Kali Linux]
• Browser [Firefox]
• Version [60.6.2]