Issue with build gcc 9.1

When we try to build open-vds library with gcc 9.1, got next error:

../OpenVDS/Optional.h:45:12: error: template placeholder type ‘const optional<...auto...>’ must be followed by a simple declarator-id 45 | optional(const std::optional& opt) : m_Value(opt.has_value() ? opt.value() : value_type()), m_HasValue(opt.has_value())

to resolve this, we change 'optional(const std::optional& opt)' on 'optional(const auto& opt)'