[Feature Request] Checkboxes toggle when backticks are present

Hi, thank you for this extension, It’s extremely helpful for me.

I’d like to request support for toggling checkboxes even when backticks are included in the same line. 

current behavior:
```md
- [x] test                 // works
- [ ] 'backtick'           // fails
- [ ] test'backtick'       // fails
- [ ] 'backtick' test      // fails
- [ ] test' backtick' test // fails
```