chore: dependabot

### Description
Add `dependabot` to bump deps.

### Blocking
`poetry` and `dependabot` are yet to be exactly compatible, as currently updating the deps would just update the `lock` file, which is not idea. `poetry` is not PEP 621 compliant [yet](https://github.com/python-poetry/poetry-core/pull/708). Add support as  when `poetry` supports so.