add configuration of gbp

debian/gbp.conf

+[DEFAULT]
+debian-branch = debian/buster
+upstream-branch = upstream/buster
+debian-tag = debian/buster/%(version)s
+upstream-tag = upstream/buster/%(version)s
+
+[buildpackage]
+git-debian-branch = debian/buster
+git-debian-tag = debian/buster/%(version)s
+git-upstream-tag = upstream/buster/%(version)s
+
+[import-orig]
+pristine-tar = True