Fix syntax error in certificate renewal endpoint

Remove duplicate 'if not asset:' line that caused IndentationError

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

plugins/endpoints/api/routes.py

@@ -3508,7 +3508,6 @@ def renew_client_certificate():
         # Row-level lock to prevent concurrent renewal requests from racing
         asset = db.session.query(Asset).with_for_update().filter_by(assetid=asset_id).first()
 
-    if not asset:
     if not asset:
         return error_response(ErrorCodes.NOT_FOUND,
                               f'Asset {asset_id} not found', http_code=404)