The issue was discovered while updating test cases in `rolldown`.
In the `.oxlintignore` file, we have:
```ignore
tests/**
```
When running the command by `lint-staged`:
```bash
oxlint -c .oxlintrc.json --ignore-path=.oxlintignore --deny-warnings "tests/function/main.js"
```
The file `main.js` gets linted despite being ignored. This happens
because, before using `Gitignore::new`, we converted paths to absolute
paths, causing the pattern `tests/**` to not match
`D:/rolldown/tests/function/main.js` correctly.
c61a383e8c/apps/oxlint/src/lint.rs (L60-L78)
