fix: selector item title cannot contains newline (#1978)

lua/avante/ui/selector/init.lua

@@ -32,7 +32,14 @@ function Selector:new(opts)
   setmetatable(o, Selector)
   o.provider = opts.provider
   o.title = opts.title
-  o.items = opts.items
+  o.items = vim
+    .iter(opts.items)
+    :map(function(item)
+      local new_item = vim.deepcopy(item)
+      new_item.title = new_item.title:gsub("\n", " ")
+      return new_item
+    end)
+    :totable()
   o.default_item_id = opts.default_item_id
   o.provider_opts = opts.provider_opts or {}
   o.on_select = opts.on_select