build: pin nixpkgs to 24.05

Author: hraban

flake.lock

@@ -16,6 +16,7 @@
   description = "Hraban's git tools";
 
   inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-24.05";
     flake-compat = {
       url = "github:edolstra/flake-compat";
       flake = false;