fix(tmux): avoid error message about window-status-current-bg
fix(tmux): avoid error message about window-status-current-bg

Silences new error in v3:

    invalid option: window-status-current-bg

wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent