@all-contributors PR are not `prettier` compliant

# Bug Report: Prettier causes CI to fail on PRs opened by all-contributors

## Describe the bug
When @all-contributors opens a PR, if `pre-commit` runs in CI and includes `prettier`, the pipeline always breaks.

The reason is that the bot generates `.all-contributorsrc` with multi-line arrays for `"files"` and `"contributions"`. Prettier automatically reformats these arrays into a single-line style, causing the CI to detect a change and fail. If pre-commit app runs in the repo, this will be fixed automatically, but, not everyone has the pre-commit app running in every single repo.

This behavior makes the repo maintainer to run pre-commit locally and push changes. This reduces the simplicity and magic of the @all-contributors bot.

**Desired behavior:** The bot should generate the contribution lists in a Prettier-compliant format (single-line arrays when possible), so that the PR passes CI without extra commits.

## To Reproduce
Steps to reproduce the behavior:

1. Ensure your repository has `pre-commit` configured with `prettier` as one of the hooks.
2. Use `@all-contributors` to add a contributor, opening a PR automatically.
3. The PR contains changes to `.all-contributorsrc` with multi-line arrays.
4. The CI pipeline runs `pre-commit run --all-files` and fails due to Prettier reformatting.

## Expected behavior
@all-contributors generates contribution arrays in a style that is already compliant with Prettier, so CI passes without manual intervention.

## Screenshots
Not applicable.

## Additional context
A workaround is to run `pre-commit` locally before merging the PR, or to add `.all-contributorsrc` to `.prettierignore`.
The long-term fix would be for the bot to respect Prettier formatting rules when generating contribution arrays.