nixos/invidious-router: Add systemd dependency on network-online.target

Otherwise, the systemd service will reliably fail on a clean boot, as
invidious-router needs a set-up network connection before starting.

(cherry picked from commit fab364e89b)

nixos/modules/services/misc/invidious-router.nix

@@ -101,6 +101,10 @@ in
   config = lib.mkIf cfg.enable {
     systemd.services.invidious-router = {
       wantedBy = [ "multi-user.target" ];
+
+      after = [ "network-online.target" ];
+      requires = [ "network-online.target" ];
+
       serviceConfig = {
         Restart = "on-failure";
         ExecStart = "${lib.getExe cfg.package} --configfile ${configFile}";