Support ARM64 with mongo 4.4

[patafx]

Hi,

i want to use your project on a Raspberry Pi.

So I need an image compatible with arm64.

I use this tutorial to do it manualy,

https://www.docker.com/blog/multi-arch-images/

and i modify the docker file like this
FROM library/mongo:4.4-bionic

It's work, i push an image on this repo : https://hub.docker.com/repository/docker/ingeli/mongodb-backup

Could you modify your continuous deployement process to do that ?