Syncthing lib is not supported by the syncthing team and they have no intention of upgrade to v2

Confirmed in Syncthing forum discussion (responded by the syncthing maintainer): https://forum.syncthing.net/t/go-module-path-for-syncthing-lib-remains-at-v1-unable-to-import-v2/25532 

As our usage of the syncthing lib is mostly just several struct types, we plan to create our own small lib, that are just sufficient for our usage in volsync.

This has to be done, before switching to syncthing binary v2