Makefile: Update debian build version

Signed-off-by: NLucas Meneghel Rodrigues <lmr@redhat.com>

Makefile

@@ -28,7 +28,7 @@ install:
 prepare-source:
 	# build the source package in the parent directory
 	# then rename it to project_version.orig.tar.gz
-	dch -D "utopic" -M -v "$(VERSION)" "Automated (make builddeb) build."
+	dch -D "vivid" -M -v "$(VERSION)" "Automated (make builddeb) build."
 	$(PYTHON) setup.py sdist $(COMPILE) --dist-dir=../
 	rename -f 's/$(PROJECT)-(.*)\.tar\.gz/$(PROJECT)_$$1\.orig\.tar\.gz/' ../*