maint: run 'make update-copyright'

[Collin Funk]

Happy new years,

I updated the copyright dates after seeing them updated in Emacs tree
[1].

Collin

[1] 
https://gitweb.git.savannah.gnu.org/gitweb/?p=gnulib.git;a=commit;h=a8482ceecf8f51571e773475a0efa9af7bb616e2