syncomat: Synthetic Contact Matrices for 200 UN Countries

<h2>What's Changed</h2> <ul> <li>Fixed bugs and general improvements :)</li> <li>Updated <code>renv</code> for better reproducibility</li> <li>Improved README for a better user experience</li> <li>A separate <a href="https://github.com/idem-lab/syncomat/blob/main/Methodology.md">Methodology page</a> is now available for a deeper dive into modifying syncomat for a user's specific needs.</li> </ul>