zeekscript: set updateScript

Upstream doesn't seem to be tagging releases anymore.

pkgs/by-name/ze/zeekscript/package.nix

@@ -2,6 +2,7 @@
   lib,
   python3,
   fetchFromGitHub,
+  unstableGitUpdater,
 }:
 
 python3.pkgs.buildPythonApplication rec {
@@ -35,6 +36,8 @@ python3.pkgs.buildPythonApplication rec {
     "zeekscript"
   ];
 
+  passthru.updateScript = unstableGitUpdater { tagPrefix = "v"; };
+
   meta = {
     description = "Zeek script formatter and analyzer";
     homepage = "https://github.com/zeek/zeekscript";