fix(tabby-agent): remove code block delimiters from commit message

[Sma1lboy]

Solving this issue #3002 by adding one line of code, xd

btw, the commit message for this one was automatically generated by Tabby.

[icycodes]

The responseMatcher RegExp should already handle this case.

/(?<=(["'`]+)?\s*)(feat|fix|docs|refactor|style|test|build|ci|chore)(\(\w+\))?:.+(?=\s*\1)/gi

[icycodes]

Ah, I see the case you provided in #3002

```
refactor(tabby-agent): remove unused utility function and update regex creation
- xxxxxxx
- xxxx
- xxxx
```

For the current response matcher:

1. It does not match multiline commit message.
2. It does not accept the scope tabby-agent, as it contains non-word char -

I think we can update the response matcher to fix it

/(?<=(["'`]+)?\s*)(feat|fix|docs|refactor|style|test|build|ci|chore)(\(\S+\))?:.+(?=\s*\1)/gis