refactor: lower lock file warning to debug

lib/workers/dep-type/package-json.js

@@ -37,7 +37,7 @@ function extractDependencies(
           logger.debug('No match');
         }
       } else {
-        logger.warn('No lock file found');
+        logger.debug('No lock file found');
       }
     } catch (err) {
       logger.debug({ currentVersion }, 'Could not find locked version');