set up treefmt action

.github/workflows/build_systems.yml

@@ -20,6 +20,4 @@ jobs:
       - name: Build default package
         run: "nixos-rebuild build --flake ./#${{ matrix.system }}"
       - name: copy to nix-cache
-        env:
-          NIX_SSHOPTS: "-vvvv"
         run: nix copy --to ssh://jeeves .#nixosConfigurations.${{ matrix.system }}.config.system.build.toplevel