Ultraplot/UltraPlot: Zenodo release

This PR integrates Zenodo with the UltraPlot repository to enable citation via DOI.

From now on, every GitHub release will be archived by Zenodo and assigned a unique DOI, allowing researchers and users to cite UltraPlot in a standardized, persistent way.

We've also added a citation file and BibTeX entry for convenience. Please refer to the GitHub "Cite this repository" section or use the provided BibTeX in your work.

This marks an important step in making UltraPlot more visible and citable in academic and scientific publications.

🔗 DOI: https://doi.org/10.5281/zenodo.15733565

Cite as

@software{vanElteren2025,
  author       = {Casper van Elteren and Matthew R. Becker},
  title        = {UltraPlot: A succinct wrapper for Matplotlib},
  year         = {2025},
  version      = {1.57.1},
  publisher    = {GitHub},
  url          = {https://github.com/Ultraplot/UltraPlot}
}

What's Changed

• Fix a few tests by @cvanelteren in https://github.com/Ultraplot/UltraPlot/pull/267
• set rng per test by @cvanelteren in https://github.com/Ultraplot/UltraPlot/pull/268
• Add xdist to image compare by @cvanelteren in https://github.com/Ultraplot/UltraPlot/pull/266
• Fix issue where view is reset on setting ticklen by @cvanelteren in https://github.com/Ultraplot/UltraPlot/pull/272
• Racing condition xdist fix by @cvanelteren in https://github.com/Ultraplot/UltraPlot/pull/273
• Replace spring with forceatlas2 by @cvanelteren in https://github.com/Ultraplot/UltraPlot/pull/275
• Revert xdist addition by @cvanelteren in https://github.com/Ultraplot/UltraPlot/pull/277
• fix: pass layout_kw in network test function by @beckermr in https://github.com/Ultraplot/UltraPlot/pull/278
• fix: this one needs a seed too by @beckermr in https://github.com/Ultraplot/UltraPlot/pull/279
• rm paren by @cvanelteren in https://github.com/Ultraplot/UltraPlot/pull/280

Full Changelog: https://github.com/Ultraplot/UltraPlot/compare/v1.57...v1.57.1