Replace outdated require('lspconfig')[server_name].setup()

[oiiiiiiii]

According to the readme of nvim-lspconfig the syntax require('lspconfig')[server_name].setup() is outdated and instead

vim.lsp.config(server_name, {
  -- Server-specific settings. See `:help lsp-quickstart`
})

should be used. This old syntax is used in the mason-lspconfig setup.

[oriori1703]

There is already a PR to implement those changes: #1475