Update copyright year to 2025

Author: pgleeson

source/_config.yml

@@ -3,7 +3,7 @@
 
 title: "Open Source Brain Documentation" # Leave empty: logo says NeuroML
 author: "the Open Source Brain project contributors"
-copyright: "2024"  # Copyright year to be placed in the footer
+copyright: "2025"  # Copyright year to be placed in the footer
 logo: images/DARK/OSB logo new dark notext.png
 
 # List bibtex source file