[/{ key not recognized as a literal

skhd-v0.3.9

When I try to use this binding:

```
shift + alt - [ : yabai -m window --space next
```

I get this error:
#57:15 expected key-literal

and although skhd is still running, it won't respond to any keypresses.

Reproduce the reported binding in skhd v0.3.9 and trace the key-literal parsing that produces “expected key-literal” at #57:15. Done means the bracket key is accepted and skhd continues responding to keypresses for this binding.

Written by the indexing model from the issue text.