avoid "Invalid tag: missing manifest digest" error message on GitLab

Makefile

@@ -4,5 +4,5 @@ TAG  = xfce
 
 all:
 	docker buildx create --use --node new-builder
-	docker buildx build --push --platform "linux/amd64" --tag "${REPO}:${TAG}" .
+	docker buildx build --provenance=false --push --platform "linux/amd64" --tag "${REPO}:${TAG}" .