Update footer for 2025

Author: francesco-ballarin

_includes/_footer.html

@@ -1,6 +1,6 @@
 <!-- FOOTER  -->
 <div id="footer_wrap" class="outer">
   <footer class="inner">
-    &copy; FEniCS Project 2024. Changes to this website can be made/suggested on <a href='https://github.com/FEniCS/web'>GitHub</a>.
+    &copy; FEniCS Project 2025. Changes to this website can be made/suggested on <a href='https://github.com/FEniCS/web'>GitHub</a>.
   </footer>
 </div>