src: use starts_with in node_dotenv.cc

PR-URL: #53539
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

src/node_dotenv.cc

@@ -135,8 +135,7 @@ void Dotenv::ParseContent(const std::string_view input) {
  }
 
  // Remove export prefix from key
- auto have_export = key.compare(0, 7, "export ") == 0;
- if (have_export) {
+ if (key.starts_with("export ")) {
  key.remove_prefix(7);
  }