Integrate the collective calendar

[utarwyn]

We are using a brand new tool to share the calendar of all events around the Green Code Initiative.
We want to display it on the website to simplify its readability and make it more visible.

📆 https://calendar.online/69d068943ef1b232261c

This EPIC can be splitted into small tasks:

• 1. Check the technical feasibility of integration with the tool
• 2. Web and mobile design
• 3. Website integration