nixos/zoneminder: update on startup if needed

nixos/modules/services/misc/zoneminder.nix

@@ -77,6 +77,8 @@ in {
         `config.services.zoneminder.database.createLocally` to true. Otherwise,
         when set to `false` (the default), you will have to create the database
         and database user as well as populate the database yourself.
+        Additionally, you will need to run `zmupdate.pl` yourself when
+        upgrading to a newer version.
       '';
 
       webserver = mkOption {
@@ -330,6 +332,8 @@ in {
             ${config.services.mysql.package}/bin/mysql < ${pkg}/share/zoneminder/db/zm_create.sql
             touch "/var/lib/${dirName}/db-created"
           fi
+
+          ${zoneminder}/bin/zmupdate.pl -nointeractive
         '';
         serviceConfig = {
           User = user;