flake: Update nix-eval-jobs and make nixpkgs follow ours

Mostly so we have one less nixpkgs fetched/copied into the store for
builds, but its seems like there might be some perf improvements to
n-e-j too.

Author: mmlb

flake.lock

@@ -19,6 +19,7 @@
     nix-editor.inputs.utils.follows = "flake-utils";
     nix-editor.url = "github:snowfallorg/nix-editor";
     nix-eval-jobs.inputs.flake-parts.follows = "flake-parts";
+    nix-eval-jobs.inputs.nixpkgs.follows = "nixpkgs";
     nix-eval-jobs.inputs.treefmt-nix.follows = "treefmt-nix";
     nix-eval-jobs.url = "github:nix-community/nix-eval-jobs";
     nix2container.inputs.nixpkgs.follows = "nixpkgs";