AK+Everywhere: Use Optional for URLParser::parse's base_url parameter

Author: https://github.com/networkException
Commit: 9915fa72fb
Pull-request: https://github.com/SerenityOS/serenity/pull/18287
Reviewed-by: https://github.com/linusg

Userland/Utilities/xml.cpp

@@ -364,7 +364,7 @@ static auto parse(StringView contents)
             .preserve_comments = true,
             .resolve_external_resource = [&](XML::SystemID const& system_id, Optional<XML::PublicID> const&) -> ErrorOr<DeprecatedString> {
                 auto base = URL::create_with_file_scheme(s_path);
-                auto url = URLParser::parse(system_id.system_literal, &base);
+                auto url = URLParser::parse(system_id.system_literal, base);
                 if (!url.is_valid())
                     return Error::from_string_literal("Invalid URL");