Bump traefik to v3

[joecorall]

Should follow this guide for regressions then do a major bump is all is well:
https://doc.traefik.io/traefik/v3.0/migration/v2-to-v3/

[joshdentremont]

I just went through the guide and I don't see anything that needs changing in the Site Template docker-compose.yml. I am able to spin up a new site using traefik 3.1.0 and it all looks OK to me.

On my existing site, I updated the docker-compose.yml to 3.1.0 and the site seems to function as normal. I would say that all we need to do is update the traefik image and we are good to go. I have tested on a new install, a dev site, and a production site and see no errors.

[joecorall]

Nice! Let's just bump it in #50

[joecorall]

Closed with #50