update FOSS4G link

Author: jmckenna

_static/foss4g2025.png

@@ -16,8 +16,8 @@ <h3>Navigation</h3>
 <p>MapServer is a project of the <a href="https://www.osgeo.org/" target="_blank">
 Open Source Geospatial Foundation</a>.</p>
 <p>
-<a href="https://2024.foss4g.org/" target="_blank">
-    <img src="{{ pathto("_static/foss4g2024.png", 1) }}" alt="FOSS4G" border="0px; text-decoration:none" />
+<a href="https://2025.foss4g.org/" target="_blank">
+    <img src="{{ pathto("_static/foss4g2025.png", 1) }}" alt="FOSS4G" border="0px; text-decoration:none" />
 </a>
 </p>
 <p>If you find MapServer useful, please consider supporting the team with a donation:</p>