This package is archived upstream:

https://github.com/henrybear327/go-proton-api

On the surface, it seems like a bad idea to ship this in forky.  Is
there any motivation for that?

It seems to be a stale (2 commits) fork of

https://github.com/ProtonMail/go-proton-api

The motivation for the fork appears to be driven by this upstream
project:

https://github.com/henrybear327/Proton-API-Bridge

However that has also been archived.

Let's look into how we can untangle the reverse dependencies to not use
this package, and replace it with a maintained fork.

/Simon