Enclose test argument with double-quotes
Enclose test argument with double-quotes

Missed this in #59 

On sway, when the screen is locked the container loses focus and hence `__done_get_focused_window_id` returns a null value, which results in the following error when `done` runs:

```
test: Missing argument at index 2

~/.config/fish/conf.d/done.fish (line 45): 
	if test "$__done_initial_window_id" != (__done_get_focused_window_id)
	  ^
in function '__done_is_process_window_focused'
	called on line 80 of file ~/.config/fish/conf.d/done.fish
in function '__done_ended'
in event handler: handler for generic event “fish_prompt”

(Type 'help test' for related documentation)
```
fisherman/done