Updated copyright headers. #229

Job	Run time
Redundancy-Check	3s
Set-Matrix-Private	3s
ubuntu-latest (r release, flags full, ubsan, debug)	2m 1s
windows-latest (r release, flags binaries)	2m 2s
macOS-latest (r release, flags binaries, ubsan)	2m 4s
ubuntu-latest (r release, flags full, covr)	1m 45s
ubuntu-latest (r devel, flags vignettes, remote)	3m 46s
	11m 44s

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