A new line in the comment text seems to cause non-match

### Jenkins and plugins versions report

Environment

```text
Same as #91
```

### What Operating System are you using (both controller, and any agents involved in the problem)?

Linux

### Reproduction steps

1. Step 1: define the triggering comment as `\\[ci-merge\\]`
2. Step 2: issue a comment of `[ci-merge]\r\n` (a new line in the end).

### Expected Results

I'd expect the comment to trigger the build, as it says in the documentation:
```
Regular expression matching

The regex is not surrounded with any markers and uses the Pattern.CASE_INSENSITIVE and Pattern.DOTALL Java flags.
```

### Actual Results

The build is not triggered.

### Anything else?

The build _is_ triggered after I edit the comment and remove the new line.

### Are you interested in contributing a fix?

_No response_