Add to Calendar Google link results in 404 on Event Registration

**Describe the bug**
When clicking the **Google** link for the _Add to Calendar_ the resultant page is a 404.

**To Reproduce**
Steps to reproduce the behavior:
1. From the tenant event homepage select an event.
2. Click the Google link next to Add to Calendar

**Expected behavior**
A calendar entry should be added to your Google Calendar

**Screenshots**

**Version**
alfio-2.0-M4