Add dependency management tool

Currently the project doesn't have any dependencies, but we will want to add some at some point. It would be easiest if we could have a tool for doing this.

I'm thinking that [hatch](https://hatch.pypa.io/latest/) might be the best choice because:

1. It's a very standard tool
2. It doesn't require dependency version pinning, unlike `poetry` and I don't think we want to pin versions here (as the plan is to use it as a library at some point)

No file or test is identified in the issue. Start by reviewing the Hatch documentation and the project's current layout, then define the dependency-management configuration and verify that the project can use Hatch to add and manage dependencies without version pinning.

Written by the indexing model from the issue text.