feat: Update pydantic to v2: NPG-0000 (#509)

# Description

Update pydantic version to 2.1 in `voting-node` and
`ideascale-importer`.

## Type of change

Please delete options that are not relevant.

- [X] New feature (non-breaking change which adds functionality)

## Checklist

- [X] My code follows the style guidelines of this project
- [X] I have performed a self-review of my code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules