Some more type cleanup

nixos/modules/tasks/filesystems.nix

@@ -121,7 +121,7 @@ in
     boot.supportedFilesystems = mkOption {
       default = [ ];
       example = [ "btrfs" ];
-      type = types.listOf types.string;
+      type = types.listOf types.str;
       description = "Names of supported filesystem types.";
     };
 

nixos/modules/tasks/kbd.nix

@@ -22,7 +22,7 @@ in
     # FIXME: still needed?
     boot.extraTTYs = mkOption {
       default = [];
-      type = types.listOf types.string;
+      type = types.listOf types.str;
       example = ["tty8" "tty9"];
       description = ''
         Tty (virtual console) devices, in addition to the consoles on

nixos/modules/tasks/network-interfaces.nix

@@ -392,7 +392,7 @@ in
 
         interfaces = mkOption {
           example = [ "eth0" "eth1" ];
-          type = types.listOf types.string;
+          type = types.listOf types.str;
           description =
             "The physical network interfaces connected by the bridge.";
         };