feat: introduction of update.sh script

maintainers/scripts/update.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+set -ex
+
+rootDir="$(git rev-parse --show-toplevel)"
+
+nixpkgs=$(nix eval --raw -f "$rootDir" "inputs.nixpkgs.outPath")
+flake=$(nix eval --raw -f "$rootDir")
+
+nix-shell --show-trace "${nixpkgs}/maintainers/scripts/update.nix" \
+  --arg include-overlays "[(import $rootDir).overlays.default]" \
+  --arg keep-going 'true' \
+  --arg predicate "(
+    let
+        prefix = \"$flake/pkgs/\";
+        prefixLen = builtins.stringLength prefix;
+    in
+        (path: pkg: (builtins.substring 0 prefixLen pkg.meta.position) == prefix)
+  )"