update mappings to be compatible with astrovim 3

mappings.lua

@@ -8,10 +8,13 @@ return {
   n = {
     -- second key is the lefthand side of the map
     -- mappings seen under group name "Buffer"
-    ["<leader>bb"] = { "<cmd>tabnew<cr>", desc = "New tab" },
-    ["<leader>bc"] = { "<cmd>BufferLinePickClose<cr>", desc = "Pick to close" },
-    ["<leader>bj"] = { "<cmd>BufferLinePick<cr>", desc = "Pick to jump" },
-    ["<leader>bt"] = { "<cmd>BufferLineSortByTabs<cr>", desc = "Sort by tabs" },
+    ["<leader>bn"] = { "<cmd>tabnew<cr>", desc = "New tab" },
+    ["<leader>bD"] = {
+      function()
+        require("astronvim.utils.status").heirline.buffer_picker(function(bufnr) require("astronvim.utils.buffer").close(bufnr) end)
+      end,
+      desc = "Pick to close",
+    },
     -- tables with the `name` key will be registered with which-key if it's installed
     -- this is useful for naming menus
     ["<leader>b"] = { name = "Buffers" },