[PHP 8.4] Add `CURL_HTTP_VERSION_3(ONLY)` constants

[Ayesh]

If the underlying Curl build supports it, setting the HTTP version should be theoretically possible. The availability of the constants do not guarantee the feature support, so declaring them in the polyfill should be same and effective.

• PR that added constants: php-src#15350
• libcurl doc on CURLOPT_HTTP_VERSION](https://curl.se/libcurl/c/CURLOPT_HTTP_VERSION.html)
• PHP.Watch: HTTP/3 Request with PHP Curl Extension
• Codex for CURL_HTTP_VERSION_3 and CURL_HTTP_VERSION_3ONLY

Fixes GH-488.