DOC update news for 1.7.1 (scikit-learn#31780)

Author: jeremiedbb

doc/templates/index.html

@@ -207,6 +207,7 @@ <h4 class="sk-card-title card-title sk-vert-align" sk-align-name="title">
         <h4 class="sk-landing-call-header">News</h4>
         <ul class="sk-landing-call-list list-unstyled">
           <li><strong>On-going development:</strong> <a href="https://scikit-learn.org/dev/whats_new/v1.8.html#version-1-8-0">scikit-learn 1.8 (Changelog)</a>.</li>
+          <li><strong>July 2025.</strong> scikit-learn 1.7.1 is available for download (<a href="whats_new/v1.7.html#version-1-7-1">Changelog</a>).</li>
           <li><strong>June 2025.</strong> scikit-learn 1.7.0 is available for download (<a href="whats_new/v1.7.html#version-1-7-0">Changelog</a>).</li>
           <li><strong>January 2025.</strong> scikit-learn 1.6.1 is available for download (<a href="whats_new/v1.6.html#version-1-6-1">Changelog</a>).</li>
           <li><strong>December 2024.</strong> scikit-learn 1.6.0 is available for download (<a href="whats_new/v1.6.html#version-1-6-0">Changelog</a>).</li>