chore: downgrade duplicate lerna failure warn

lib/workers/branch/lerna.js

@@ -42,7 +42,7 @@ async function generateLockFiles(manager, tmpDir, env) {
       'Generated lockfile'
     );
   } catch (err) /* istanbul ignore next */ {
-    logger.warn(
+    logger.info(
       {
         err,
         stdout,