💡 [REQUEST] - Switch to an `src/` layout (vs a flat layout currently)?

### Summary

The `/src` layout looks like a de-facto standard these days and can prevent common errors.

### Basic Example

See:
- https://packaging.python.org/en/latest/discussions/src-layout-vs-flat-layout/
- https://www.pyopensci.org/python-package-guide/package-structure-code/python-package-structure.html

### Screenshots

_No response_

### Drawbacks

Let's test a full development and release workflow, and check everything still behaves as expected.

### Unresolved questions

_No response_

### Code of Conduct

- [X] I agree to follow this project's Code of Conduct