resolves error on CI run https://git.fediversity.eu/Fediversity/Fediversity/actions/runs/1026:
```
123456 error: attempt to call something which is not a function but a path: /nix/store/93yyf22vw60l1j3l6h02c99p93lp55q5-source/panel
at /nix/store/93yyf22vw60l1j3l6h02c99p93lp55q5-source/machines/dev/fedi201/fedipanel.nix:13:6:
12| imports = [
13| (../../../panel { }).module
| ^
14| "${sources.home-manager}/nixos"```
```
Reviewed-on: Fediversity/Fediversity#468
closes#93.
note that this includes classes:
- `nixos`
- `nixosTest`
- `nixops4Resource`
- `nixops4Deployment`
.. and my (made-up, as per the [docs](https://ryantm.github.io/nixpkgs/module-system/module-system/#module-system-lib-evalModules-param-class)):
- `nix-unit`
- `package`
.. while i did not manage to cover:
- service tests, given `pkgs.nixosTest` seemed to not actually like `_class = "nixosTest"` (?!)
... nor #93's mentioned destructured arguments for that matter, as per Fediversity/Fediversity#93 (comment) - let me know if that is still desired as well.
Reviewed-on: Fediversity/Fediversity#398
Reviewed-by: Valentin Gagarin <valentin.gagarin@tweag.io>
Co-authored-by: Kiara Grouwstra <kiara@procolix.eu>
Co-committed-by: Kiara Grouwstra <kiara@procolix.eu>
later we may want to distinguish dev vs host as well, tho eventually we expect not to have hard-coded machines anyway.
split off from #319.
Reviewed-on: Fediversity/Fediversity#367
Co-authored-by: Kiara Grouwstra <kiara@procolix.eu>
Co-committed-by: Kiara Grouwstra <kiara@procolix.eu>
