-cword stopped working

NVIM version: v0.6.1
vim-grepper version: 2b93535752ffcb312f9fab73d90e80dc9f2e60fc
OS: Mac 12.3.1
git: 2.33.0

I've been using this option for a while but I've noticed it's stopped working recently:
```
noremap :Grepper -cword -noprompt
```
---
If run this command `Grepper -cword`, I get:
```
git grep -nGI> '\\bnoremap\\b'
```
When I press enter, it won't match with any record

If run it again and this time, remove one set of `\` like this:
```
git grep -nGI> '\bnoremap\b'
```
it finds all the matches.

Reproduce the issue with the shown `Grepper -cword` command and the git backend. Trace how the cword value is escaped before the displayed git grep command is built, then verify that the generated command matches the manually corrected form and finds the expected records.

Written by the indexing model from the issue text.