Add pob update script

scripts/update-pob.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+set -eo pipefail
+
+# TODO: Update pobfrontend as well?
+
+if [ -z "$1" ]; then
+    nurl_output=$(nurl -j https://github.com/PathOfBuildingCommunity/PathOfBuilding 2>/dev/null)
+    rev=$(jq '.args.rev' <<< "$nurl_output")
+else
+    nurl_output=$(nurl -j https://github.com/PathOfBuildingCommunity/PathOfBuilding "$1" 2>/dev/null)
+fi
+
+hash=$(jq '.args.hash' <<< "$nurl_output")
+echo "Updating pob to $rev"
+
+# Find lines to replace
+line_numbers=$(grep -Fn "rev =" packages/pob.nix| cut -d":" -f1)
+line_data=$(head -n1 <<< "$line_numbers")
+
+sed -i "${line_data}s/.*/  rev = $rev;/" packages/pob.nix
+nixfmt packages/pob.nix