fix(docker): info not warn for no labels

lib/datasource/docker/index.js

@@ -383,8 +383,11 @@ async function getLabels(registry, repository, tag) {
     let labels = {};
     // istanbul ignore if
     if (!manifest.config) {
-      logger.warn({ manifest }, 'Docker manifest error: no config');
-      throw new Error('registry-failure');
+      logger.info(
+        { dockerRepository: repository, tag, manifest },
+        'Docker manifest error: no config'
+      );
+      return {};
     }
     const configDigest = manifest.config.digest;
     const headers = await getAuthHeaders(registry, repository);