refactor(nix): nix-filter -> lib.fileset

with our own use of `map`, this is basically a drop-in replacement for
nix-filter, but already in nixpkgs!

Signed-off-by: seth <getchoo@tuta.io>

nix/distribution.nix

@@ -26,24 +26,8 @@
     overlays.default = final: prev: let
       version = builtins.substring 0 8 self.lastModifiedDate or "dirty";
 
-      filteredSelf = inputs.nix-filter.lib.filter {
-        root = ../.;
-        include = [
-          "buildconfig"
-          "cmake"
-          "launcher"
-          "libraries"
-          "program_info"
-          "tests"
-          ../COPYING.md
-          ../CMakeLists.txt
-        ];
-      };
-
       # common args for prismlauncher evaluations
       unwrappedArgs = {
-        self = filteredSelf;
-
         inherit (inputs) libnbtplusplus;
         inherit ((final.darwin or prev.darwin).apple_sdk.frameworks) Cocoa;
         inherit version;