vim:coc: Select first item before confirming

I believe I had the problem in the past that the completion wouldn't
automatically select the first entry but simply display the menu. Thus
it would simply insert a new line when pressing return to accept it.

Unfortunately I didn't commit it back then and I can't reproduce it now.
But it doesn't not hurt so I commit it to be safe.

.config/vim/vimrc.d/25-coc.vim

@@ -64,7 +64,7 @@ endif
 
 " Make <CR> to accept selected completion item or notify coc.nvim to format
 " <C-g>u starts a new undo break, please make your own choice.
-inoremap <silent><expr> <CR> coc#pum#visible() ? coc#pum#confirm()
+inoremap <silent><expr> <CR> coc#pum#visible() ? coc#_select_confirm()
                               \: "\<C-g>u\<CR>\<c-r>=coc#on_enter()\<CR>"
 
 " Use `[g` and `]g` to navigate diagnostics