add ffmpeg in path for nextcloud apps

modules/nextcloud-server.nix

@@ -189,6 +189,9 @@ in
       forceSSL = true;
     };
 
+    # Needed for a few apps. Would be nice to avoid having to put that in the environment and instead override https://github.com/NixOS/nixpkgs/blob/261abe8a44a7e8392598d038d2e01f7b33cf26d0/nixos/modules/services/web-apps/nextcloud.nix#L1035
+    environment.systemPackages = [ pkgs.ffmpeg ];
+
     systemd.services.phpfpm-nextcloud.serviceConfig = {
       # Setup permissions needed for backups, as the backup user is member of the jellyfin group.
       UMask = lib.mkForce "0027";