fix: pass through migratedConfig warnings

lib/workers/repository/init/config.js

@@ -96,6 +96,11 @@ async function mergeRenovateConfig(config) {
       .join(', ');
     throw error;
   }
+  if (migratedConfig.warnings) {
+    returnConfig.warnings = returnConfig.warnings.concat(
+      migratedConfig.warnings
+    );
+  }
   delete migratedConfig.errors;
   delete migratedConfig.warnings;
   logger.debug({ config: migratedConfig }, 'renovate.json migrated config');