palemoon-bin: Add version test

pkgs/applications/networking/browsers/palemoon/bin.nix

···
 , libpulseaudio
 , makeDesktopItem
 , wrapGAppsHook
+, testers
+, palemoon-bin
 }:
 
 stdenv.mkDerivation rec {
···
     )
     wrapGApp $out/lib/palemoon/palemoon
   '';
+
+  passthru.tests.version = testers.testVersion {
+    package = palemoon-bin;
+  };
 
   meta = with lib; {
     homepage = "https://www.palemoon.org/";