fix: E5108 error in command line buffer

[towry]

error detail:

E5108: Error executing lua ...are/nvim/lazy/smart-splits.nvim/lua/smart-splits/api.lua:472: E11: Invalid in command-line window; <CR> executes, CTRL-C quits
stack traceback:
        [C]: in function 'nvim_set_current_win'
        ...are/nvim/lazy/smart-splits.nvim/lua/smart-splits/api.lua:472: in function 'resize_up'
        [string ":lua"]:1: in main chunk

Steps to repro:

1. q: to open cmd win.
2. try to resize the cmd win.

[mrjones2014]

Simple and safe enough change, thanks! I didn't consider that use case since I don't really use that feature of Neovim often.