common: Fix current year in copyright

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swh/web/api/apidoc.py

swh/web/api/apiresponse.py

swh/web/api/apiurls.py

swh/web/api/renderers.py

swh/web/api/urls.py

swh/web/api/utils.py

swh/web/api/views/content.py

swh/web/api/views/directory.py

swh/web/api/views/entity.py

swh/web/api/views/origin.py

swh/web/api/views/person.py

swh/web/api/views/release.py

swh/web/api/views/revision.py

swh/web/api/views/stat.py

swh/web/api/views/utils.py

swh/web/api/views/vault.py

swh/web/browse/browseurls.py

swh/web/browse/urls.py

swh/web/browse/utils.py