This replaces the previous arclint linter for checking the copyright
year in license headers with a gitea workflow job.
As the date of last edit might differ from commit date due to reverts
the copyright linter is run against a base commit.
The python script doing the heavy lifting is written by @Dunedan.
Signed-off-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>
Co-Authored-by: Dunedan <dunedan@phoenitydawn.de>
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