Remove the auto-generated copyright years from the docs footer.

[wRAR]

Closes #5019.

Follows https://hynek.me/til/copyright-years/ / https://www.linuxfoundation.org/blog/blog/copyright-notices-in-open-source-software-projects / https://daniel.haxx.se/blog/2023/01/08/copyright-without-years/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.87%. Comparing base (1d11ea3) to head (15835e3).
Report is 5 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6322      +/-   ##
==========================================
+ Coverage   83.92%   88.87%   +4.94%     
==========================================
  Files         161      161              
  Lines       11972    11972              
  Branches     1865     1929      +64     
==========================================
+ Hits        10048    10640     +592     
+ Misses       1588      980     -608     
- Partials      336      352      +16     

see 26 files with indirect coverage changes