nile: fix passthru.updateScript

The update script was erroneously carried over from the gogdl
derivation code, upon which this derivation was based initially.  It
should be using unstableGitUpdater instead.

Date in current "unstable" version string corrected to UTC.

pkgs/games/nile/default.nix

@@ -1,5 +1,5 @@
 { lib
-, writeScript
+, unstableGitUpdater
 , buildPythonApplication
 , fetchFromGitHub
 , pythonOlder
@@ -15,7 +15,7 @@
 
 buildPythonApplication rec {
   pname = "nile";
-  version = "unstable-2023-10-03";
+  version = "unstable-2023-10-02";
   format = "pyproject";
 
   src = fetchFromGitHub {
@@ -55,30 +55,5 @@ buildPythonApplication rec {
     maintainers = with maintainers; [ aidalgol ];
   };
 
-  # Upstream does not create git tags when bumping the version, so we have to
-  # extract it from the source code on the main branch.
-  passthru.updateScript = writeScript "gogdl-update-script" ''
-    #!/usr/bin/env nix-shell
-    #!nix-shell -i bash -p curl gnused jq common-updater-scripts
-    set -eou pipefail;
-
-    owner=imLinguin
-    repo=nile
-    path='nile/__init__.py'
-
-    version=$(
-      curl --cacert "${cacert}/etc/ssl/certs/ca-bundle.crt" \
-      https://raw.githubusercontent.com/$owner/$repo/main/$path |
-      sed -n 's/^\s*version\s*=\s*"\([0-9]\.[0-9]\.[0-9]\)"\s*$/\1/p')
-
-    commit=$(curl --cacert "${cacert}/etc/ssl/certs/ca-bundle.crt" \
-      https://api.github.com/repos/$owner/$repo/commits?path=$path |
-      jq -r '.[0].sha')
-
-    update-source-version \
-      ${pname} \
-      "$version" \
-      --file=./pkgs/games/nile/default.nix \
-      --rev=$commit
-  '';
+  passthru.updateScript = unstableGitUpdater { };
 }