vendor : update cpp-httplib to 0.42.0

[cabelo]

Overview

Additional information

Requirements

• I have read and agree with the contributing guidelines
• AI usage disclosure:

What's Changed

v0.42.0

• test: WebSocketIntegrationTest.SocketSettings: do not set AF_INET
• Refactor SSLVerifierResponse to enum class and add get_param_values method
  to Request

v0.41.0

• Replace httplib::any / std::map<std::string, httplib::any> based res.user_data with a
  new type-safe UserData class that provides set() / get() API
• Add parse_url utility function with UrlComponents struct for parsing URLs into
  scheme, host, port, path, and query components
• [cmake] Allow using pre-existing zstd::libzstd target if it already exists, useful for
  projects that bundle their own zstd
• Add header parser and URL parser fuzzers for OSS-Fuzz coverage improvement