vrcadvert: add update script

pkgs/by-name/vr/vrcadvert/package.nix

@@ -29,6 +29,8 @@ buildDotnetModule rec {
   ];
   versionCheckProgram = "${placeholder "out"}/bin/VrcAdvert";
 
+  passthru.updateScript = ./update.sh;
+
   meta = {
     description = "Advertise your OSC app through OSCQuery";
     homepage = "https://github.com/galister/VrcAdvert";

pkgs/by-name/vr/vrcadvert/update.sh

@@ -0,0 +1,8 @@
+#!/usr/bin/env nix-shell
+#!nix-shell --pure -i bash -p bash nix nix-update git cacert
+set -eo pipefail
+
+prev_version=$(nix eval --raw -f. vrcadvert.version)
+nix-update vrcadvert
+[[ $(nix eval --raw -f. vrcadvert.version) == "$prev_version" ]] ||
+  $(nix-build . -A vrcadvert.fetch-deps --no-out-link)