necesse-server: add udpate script

pkgs/by-name/ne/necesse-server/package.nix

@@ -39,6 +39,8 @@ stdenvNoCC.mkDerivation {
     runHook postInstall
   '';
 
+  passthru.updateScript = ./update.sh;
+
   meta = {
     homepage = "https://necessegame.com/server/";
     description = "Dedicated server for Necesse";

pkgs/by-name/ne/necesse-server/update.sh

@@ -0,0 +1,15 @@
+#!/usr/bin/env nix-shell
+#!nix-shell -i bash -p curl pup common-updater-scripts
+
+set -eu -o pipefail
+
+version=$(
+    curl -s http://www.necessegame.com/server \
+        | pup 'a[href*="linux64"] text{}' \
+        | awk -F'[v ]' '/Linux64/ {print $4"-"$6}' \
+        | sort -Vu \
+        | tail -n1
+)
+
+[[ $version =~ ^[0-9]+\.[0-9]+\.[0-9]+\-[0-9]+$ ]] \
+    && update-source-version necesse-server "$version"