This update for civetweb fixes the following issues:

- explicit compiler options for websockets, zlib, ssl and ssl v3 added

- Update to version 1.16:
  * Enable IPv6 as default when using CMake
  * Define error codes for mg_start2, mg_start_domain2, mg_connect_client2
  * Fixes for OpenSSL 3.0 support
  * Add support for Mbed TLS v3.0.0
  * WebDAV should understand Windows File Explorer (experimental)
  * Accept HTTP basic authentication
  * Make pattern matching function availible in the public interface
  * Make base64 encoding and decoding functions available
  * Various fixes for HTTP/2 support
  * Additional examples
  * Fixes and updates to existing examples
  * Fix spelling errors in code and documentation
  * Remove Conan support
  * Known Issues:
    The WebDAV support when using the Windows Explorer as client has various limitations when renaming or moving files and folders. 
    In particular file names in non-latin characters may break when running the server on Linux and connecting with the Windows Explorer.