Image in the readme

**Copied from [PsiQ/bartiq #161](https://github.com/PsiQ/bartiq/issues/161)**

## Describe the bug
Image of alias sampling in readme doesn't display properly on neither on GH nor on [PyPI](https://pypi.org/project/bartiq/).

<img width="785" alt="Image" src="https://github.com/user-attachments/assets/1c6f9155-57b3-4917-81bc-832bf35763d2" />