fix: adapt to Nvim deprecations in 0.10 (#3109)

plugin/telescope.lua

@@ -116,7 +116,13 @@ end, {
     local n = #l - 2
 
     if n == 0 then
-      local commands = vim.tbl_flatten { builtin_list, extensions_list }
+      local commands = { builtin_list, extensions_list }
+      -- TODO(clason): remove when dropping support for Nvim 0.9
+      if vim.fn.has "nvim-0.10" then
+        commands = vim.iter(commands):flatten():totable()
+      else
+        commands = vim.tbl_flatten(commands)
+      end
       table.sort(commands)
 
       return vim.tbl_filter(function(val)