tests/nixpkgs-module: only import the minimal modules for test

Instead of importing the full set of top-level nixvim modules, only
import the nixpkgs-module and its direct dependencies.

tests/nixpkgs-module.nix

@@ -10,18 +10,24 @@ let
 
   defaultPkgs = pkgs;
 
+  # Only imports the bare minimum modules, to ensure we are not accidentally evaluating `pkgs.*`
   evalModule =
     name: module:
-    lib.nixvim.modules.evalNixvim {
+    lib.evalModules {
       modules = lib.toList module ++ [
         {
+          _module.check = false;
+          flake = self;
           test = {
             inherit name;
             buildNixvim = false;
             runNvim = false;
             runCommand = runCommandLocal;
           };
         }
+        ../modules/misc
+        ../modules/top-level/test.nix
+        ../modules/top-level/nixpkgs.nix
       ];
     };