[nvim] Removes copilot.nvim because copilot.lua is already available

home-manager/features/neovim/config/lua/plugins/copilot.lua

@@ -1,6 +0,0 @@
-return {
-  -- Add Github Copilot plugin.
-  -- It still needs to be configured with `:Copilot setup`.
-  -- See `:help copilot` for more information
-  { "github/copilot.vim" },
-}