VersionLibrary version and User-Agent header support. Per RFC 9110 Section 10.1.5 and Recommendation #30: Provides a default User-Agent header for HTTP requests.
Default User-Agent header value. Format: "ocaml-requests/VERSION (OCaml OCAML_VERSION)" Example: "ocaml-requests/0.1.0 (OCaml 5.2.0)"
Per RFC 9110 Section 10.1.5, this helps server-side debugging and monitoring. The User-Agent is automatically added to requests unless the user provides their own.