add: diffnav, gh-dash, lazygit, k9s overrides

these are all overlays that were part of my nix config before i created
my nur. i am putting them here to reduce build time when building my nix
config

flake.nix

@@ -11,6 +11,10 @@
       url = "github:oxalica/rust-overlay";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+    go-overlay = {
+      url = "github:purpleclay/go-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
 
     hildibrand.url = "git+https://scm.wyattjmiller.com/wymiller/hildibrand.git";
     hildibrand.inputs.nixpkgs.follows = "nixpkgs";
@@ -18,7 +22,7 @@
     caitsith.inputs.nixpkgs.follows = "nixpkgs";
   };
 
-  outputs = inputs@{ self, nixpkgs, home-manager, darwin, rust-overlay, ... }:
+  outputs = inputs@{ self, nixpkgs, home-manager, darwin, rust-overlay, go-overlay, ... }:
     let
       supportedSystems = [
         "x86_64-linux"
@@ -61,6 +65,7 @@
 
       overlays.default = nixpkgs.lib.composeManyExtensions [
         rust-overlay.overlays.default
+        go-overlay.overlays.default
         (import ./overlays)
       ];
       homeManagerModules = import ./modules/home-manager self;