fix(users/multi/home): re-add overridden htop package to home-manager configuration.

I previously removed my local package set from my HM config while the
latter was being made readTree compatible. Now that both the HM config
and the local package set can be built with readTree, I can re-enable
the locally-overridden htop package.

Change-Id: I77e20248c010bc7027e0b0a3164ec48d6ec29f31
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2132
Tested-by: BuildkiteCI
Reviewed-by: multi <depot@in-addr.xyz>

users/multi/home/configs/whitby.nix

@@ -2,6 +2,7 @@
 
 let
   nixpkgs = import pkgs.nixpkgsSrc {};
+  localpkgs = depot.users.multi.pkgs;
 
   # use the depot checkout in my home directory, to make hacking around easier,
   # instead of the depot checkout sitting in the nix stores
@@ -57,6 +58,7 @@ in
     nixpkgs.strace
     nixpkgs.file
     nixpkgs.pciutils
+    localpkgs.htop
   ];
 
   home.file = {