wiki-js: add update script

pkgs/servers/web-apps/wiki-js/default.nix

···
     runHook postInstall
   '';
 
-  passthru.tests = { inherit (nixosTests) wiki-js; };
+  passthru = {
+    tests = { inherit (nixosTests) wiki-js; };
+    updateScript = ./update.sh;
+  };
 
   meta = with lib; {
     homepage = "https://js.wiki/";

pkgs/servers/web-apps/wiki-js/update.sh

···
+#!/usr/bin/env nix-shell
+#!nix-shell -i bash -p curl common-updater-scripts
+
+oldVersion="$(nix-instantiate --eval -E "with import ./. {}; lib.getVersion wiki-js" | tr -d '"')"
+latestTag="$(git ls-remote --tags --sort="v:refname" https://github.com/Requarks/wiki.git | tail -1 | awk '{ print $2 }' | sed -E "s,^refs/tags/v(.*)$,\1,")"
+
+targetVersion="${1:-$latestTag}"
+if [ ! "${oldVersion}" = "${targetVersion}" ]; then
+  update-source-version wiki-js "${targetVersion}"
+  nix-build -A wiki-js
+else
+  echo "wiki-js is already up-to-date"
+fi