nixos/tandoor-recipes: improve manage script

This is mirroring the way the manage script is created in the paperless
module, which is more robust to special characters.

nixos/modules/services/misc/tandoor-recipes.nix

@@ -17,14 +17,11 @@ let
     lib.mapAttrs (_: toString) cfg.extraConfig
   );
 
-  manage =
-    let
-      setupEnv = lib.concatStringsSep "\n" (mapAttrsToList (name: val: "export ${name}=\"${val}\"") env);
-    in
-    pkgs.writeShellScript "manage" ''
-      ${setupEnv}
-      exec ${pkg}/bin/tandoor-recipes "$@"
-    '';
+  manage = pkgs.writeShellScript "manage" ''
+    set -o allexport # Export the following env vars
+    ${lib.toShellVars env}
+    exec ${pkg}/bin/tandoor-recipes "$@"
+  '';
 in
 {
   meta.maintainers = with maintainers; [ ambroisie ];