New upstream release (Closes: #GOS-278)

Change branch name to new version and edit date in copyright information.

Author: sh-gb

debian/gbp.conf

@@ -1,6 +1,6 @@
 [DEFAULT]
 debian-branch = gos20.08
-upstream-branch = python-gvm-v20.9.1
+upstream-branch = python-gvm-v21.1.3
 upstream-tree = branch
 
 [buildpackage]

debian/patches/add_setup_py.patch

@@ -2,7 +2,7 @@
 +++ /setup.py
 @@ -0,0 +1,62 @@
 +# -*- coding: utf-8 -*-
-+# Copyright (C) 2018 Greenbone Networks GmbH
++# Copyright (C) 2018-2021 Greenbone Networks GmbH
 +#
 +# SPDX-License-Identifier: GPL-3.0-or-later
 +#