docs(licence): update licence dates

cubicweb_celerytask/ccplugin.py

 # -*- coding: utf-8 -*-
-# copyright 2016 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# copyright 2016-2021 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
 # contact http://www.logilab.fr -- mailto:contact@logilab.fr
 #
 # This program is free software: you can redistribute it and/or modify it under

cubicweb_celerytask/entities.py

 # -*- coding: utf-8 -*-
-# copyright 2016 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# copyright 2016-2021 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
 # contact http://www.logilab.fr -- mailto:contact@logilab.fr
 #
 # This program is free software: you can redistribute it and/or modify it under

cubicweb_celerytask/hooks.py

 # -*- coding: utf-8 -*-
-# copyright 2016 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# copyright 2016-2021 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
 # contact http://www.logilab.fr -- mailto:contact@logilab.fr
 #
 # This program is free software: you can redistribute it and/or modify it under

cubicweb_celerytask/migration/postcreate.py

 # -*- coding: utf-8 -*-
-# copyright 2016 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# copyright 2016-2021 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
 # contact http://www.logilab.fr -- mailto:contact@logilab.fr
 #
 # This program is free software: you can redistribute it and/or modify it under

cubicweb_celerytask/migration/utils.py

 # -*- coding: utf-8 -*-
-# copyright 2018 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# copyright 2018-2021 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
 # contact http://www.logilab.fr -- mailto:contact@logilab.fr
 #
 # This program is free software: you can redistribute it and/or modify it under

cubicweb_celerytask/schema.py

 # -*- coding: utf-8 -*-
-# copyright 2016 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# copyright 2016-2021 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
 # contact http://www.logilab.fr -- mailto:contact@logilab.fr
 #
 # This program is free software: you can redistribute it and/or modify it under

cubicweb_celerytask/testutils.py

-# copyright 2016 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# copyright 2016-2021 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
 # contact http://www.logilab.fr -- mailto:contact@logilab.fr
 #
 # This program is free software: you can redistribute it and/or modify it under

cubicweb_celerytask/views.py

 # -*- coding: utf-8 -*-
-# copyright 2016 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# copyright 2016-2021 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
 # contact http://www.logilab.fr -- mailto:contact@logilab.fr
 #
 # This program is free software: you can redistribute it and/or modify it under

setup.py

 #!/usr/bin/env python
 # pylint: disable=W0142,W0403,W0404,W0613,W0622,W0622,W0704,R0904,C0103,E0611
 #
-# copyright 2003-2016 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# copyright 2003-2021 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
 # contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
 #
 # This file is part of a CubicWeb cube.

test/test_celerytask.py

 # coding: utf-8
-# copyright 2016 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# copyright 2016-2021 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
 # contact http://www.logilab.fr -- mailto:contact@logilab.fr
 #
 # This program is free software: you can redistribute it and/or modify it under

test/test_hooks.py

 # -*- coding: utf-8 -*-
-# copyright 2018 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# copyright 2018-2021 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
 # contact http://www.logilab.fr -- mailto:contact@logilab.fr
 #
 # This program is free software: you can redistribute it and/or modify it under