feat(LSP): Delete erroneous argument `buffer`

The argument `buffer` us used for another type of autocmd's, those with
whole buffer scope.

nvim/lua/lsp/diagnostics.lua

@@ -26,7 +26,6 @@ vim.api.nvim_create_autocmd("LspAttach", {
     local client = vim.lsp.get_client_by_id(args.data.client_id)
     vim.api.nvim_create_autocmd({ "CursorHold", "CursorHoldI" }, {
       group = vim.api.nvim_create_augroup("Diagnostics", { clear = true }),
-      buffer = bufnr,
       callback = function()
         vim.diagnostic.open_float({
           focusable = false,