chore: fix badges (#335)

Author: gdalle

README.md

@@ -8,8 +8,8 @@
 [![Dev Documentation](https://img.shields.io/badge/docs-dev-blue.svg)](https://juliadiff.org/SparseMatrixColorings.jl/dev/)
 [![Code Style: Blue](https://img.shields.io/badge/code%20style-blue-4495d1.svg)](https://github.com/JuliaDiff/BlueStyle)
 [![arXiv](https://img.shields.io/badge/arXiv-2505.07308-b31b1b.svg)](https://arxiv.org/abs/2505.07308)
-[![DOI](https://zenodo.org/badge/801999408.svg)](https://zenodo.org/doi/10.5281/zenodo.11314275)
-[![All Contributors](https://img.shields.io/github/all-contributors/JuliaDiff/SparseMatrixColorings.jl?color=ee8449&style=flat-square)](#contributors)
+[![DOI](https://img.shields.io/badge/DOI-10.5281/zenodo.11314275-blue.svg)](https://zenodo.org/doi/10.5281/zenodo.11314275)
+[![All Contributors](https://img.shields.io/github/all-contributors/JuliaDiff/SparseMatrixColorings.jl?color=ee8449)](#contributors)
 
 Coloring algorithms for sparse Jacobian and Hessian matrices.