nixpkgs/neovim: fix blink.cmp not falling back <CR> to mini.pairs

.config/nixpkgs/neovim/config/lua/user/plugins/completion.lua

@@ -29,7 +29,7 @@ blink_cmp.setup({
     },
   },
   keymap = {
-    ['<Enter>'] = { 'select_and_accept', 'fallback' },
+    ['<CR>'] = { 'select_and_accept', 'fallback_to_mappings' },
     ['<C-u>'] = { 'scroll_documentation_up', 'fallback' },
     ['<C-d>'] = { 'scroll_documentation_down', 'fallback' },
   },