Refresh the automatically detected licensing information

Signed-off-by: Ritesh Raj Sarraf <ritesh.sarraf@collabora.co.uk>

debian/apertis/copyright

+Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
+
+Files: *
+Copyright: 2014-2020, gRPC authors.
+License: Apache-2.0
+
+Files: debian/*
+Copyright: 2015, 2016, 2020, Dmitry Smirnov <onlyjob@debian.org>
+License: GPL-3+ or Apache-2.0
+
+Files: debian/missing-sources/*
+Copyright: 2020, Google LLC
+License: Apache-2.0
+
+Files: debian/missing-sources/grpc/*
+Copyright: 2015, 2016, 2018, The gRPC Authors
+License: Apache-2.0
+
+Files: vet.sh
+Copyright: 2014-2019 Google Inc.
+License: Apache-2.0