Header parsing assumes whitespace after colon

RFC7230 (HTTP 1.1) 3.2 "Header fields" specifies that whitespace between
colon and value is optional, but http_client_asio::read_headers started
reading the value at one after the colon, assuming there would always be
exactly one space.

Author: stewartbright

Release/src/http/client/http_client_asio.cpp

@@ -1123,7 +1123,6 @@ class asio_context : public request_context, public std::enable_shared_from_this
             if (colon != std::string::npos)
             {
                 auto name = header.substr(0, colon);
-                auto value = header.substr(colon + 2, header.size() - (colon + 3)); // also exclude '\r'
                 boost::algorithm::trim(name);
                 boost::algorithm::trim(value);