update postgis docker image

[nsteins]

On a fresh install of the repo, I was unable to build the project. The build would fail during the step

=> ERROR [postgres 2/3] RUN apt-get update && apt-get install -y --no-install-recommends

Digging deeper, it would appear the build was failing on apt calls update and install with 404 responses. I believe that is because db/Dockerfile is built on this no-longer maintained image: mdillon/postgis. I think that image is built on Debian 9 (stretch) which has surpassed its LTS timeframe.

Fortunately, it appears there is now an official and maintained postgis image. Changing the first line of db/Dockerfile to FROM postgis/postgis:13-3.3 resolved my build issues.

You could go ahead and skip to postgres 15 with this update, to jump to the latest stable version, but the other dockerfiles seemed to be on 13, which is why I chose that

[jeancochrane]

Thanks so much for this Nat, I'll take a look at this and your other PR tomorrow!

[jeancochrane]

Oops, I did not in fact take a look at this last year 🤦🏻‍♀️ Just popping in to say this is on my mind again and I hope to find some time to bring it up to date in the coming weeks!

[jeancochrane]

I very much appreciate the work that went into this PR! Enough has changed even in the past year that I decided to just do a fresh pass at database dependencies in #56. Everything should build properly now, but feel free to open a new PR if there are problems with the new versions.