[search] Update copyright year in the searchfield.html header. (#12110)

Co-authored-by: Bénédikt Tran <[email protected]>

sphinx/themes/basic/searchfield.html

@@ -7,7 +7,7 @@
  extra heading ("Quick search"). Instead, it uses a placeholder text
  in the search field.
 
- :copyright: Copyright 2007-2022 by the Sphinx team, see AUTHORS.
+ :copyright: Copyright 2007-2024 by the Sphinx team, see AUTHORS.
  :license: BSD, see LICENSE for details.
 #}
 {%- if pagename != "search" and builder != "singlehtml" %}