nix/modules/knot: remove firewall settings

firewall should be handled by users. this change will allow setting
non-22 ssh ports

Close: #269
Signed-off-by: Seongmin Lee <[e-mail]>

nix/modules/knot.nix

···
           description = "User that hosts git repos and performs git operations";
         };
 
-        openFirewall = mkOption {
-          type = types.bool;
-          default = true;
-          description = "Open port 22 in the firewall for ssh";
-        };
-
         stateDir = mkOption {
           type = types.path;
           default = "/home/${cfg.gitUser}";
···
           Restart = "always";
         };
       };
-
-      networking.firewall.allowedTCPPorts = mkIf cfg.openFirewall [22];
     };
   }