fix: Use only the first line for the telescope picker entry

[nazo6]

While using the fidget telescope extension, I noticed that the following error occasionally occurs.

vim.schedule callback: .../nvim-data/lazy/telescope.nvim/lua/telescope/pickers.lua:1469: Cursor position outside buffer
stack traceback:
        [C]: in function 'nvim_win_set_cursor'
        .../nvim-data/lazy/telescope.nvim/lua/telescope/pickers.lua:1469: in function 'fn'
        vim/_editor.lua:296: in function <vim/_editor.lua:295>

This error seems to occur when the telescope picker entry contains line breaks. I fixed this by using only the first line of entry.message.