chore: log when setting npmrc

lib/workers/package-file/index.js

@@ -34,6 +34,7 @@ async function renovatePackageFile(packageFileConfig) {
   });
   logger.debug('renovatePakageFile()');
   if (config.npmrc) {
+    logger.debug('Setting .npmrc');
     npmApi.setNpmrc(config.npmrc);
   }
   let upgrades = [];