nvim: plugins: Add support for cabal-fmt

nvim/.config/nvim/lua/plugins.lua

@@ -65,6 +65,7 @@ local init = function ()
   -- Language support & syntax highlighting
   use 'mfussenegger/nvim-lint'
   use 'lvimuser/lsp-inlayhints.nvim'
+  use 'sdiehl/vim-cabalfmt'
   -- treesitter based syntax highlighting
   use {
     'nvim-treesitter/nvim-treesitter',