maint: run 'make update-copyright'

[Collin Funk]

Happy new years,

I updated the copyright dates after doing the same in Gnulib [1].

Collin

[1] 
https://gitweb.git.savannah.gnu.org/gitweb/?p=coreutils.git;a=commit;h=73d3a49f45770c45808e4fdab35ae4fe248a3cd9