fix lsp sumneko_lua crach

[ayoubelmhamdi]

I don't know why I should add {} to the table to avoid sumneko_lua crash

require'lsp_signature'.setup(cfg)

==>
require'lsp_signature'.setup({cfg})

[ray-x]

I think there might be something releated with your environment. Would you send me a minimum vimrc for me to verify? I did not see this issue before.

[Zeioth]

@ray-x This PR can probably be closed. No one found this issue in 2 years.