[SPDM 1.3] `Request attributes` of `GET_CERTIFICATE` request should not be hard code with zero.

[Zhiqiang520]

Request attributes of GET_CERTIFICATE request should not be hard code with zero. I think maybe we should add one new parameter Request attributes into libspdm_try_get_certificate() function just like the parameter slot_id.

Refer to the paragraph 382 Table 38 — GET_CERTIFICATE request message format In DSP0274_1.3.0.pdf.

https://github.com/DMTF/libspdm/blob/743f1db79a7c3fcf7f1784546e8fe0f20e0cc95a/library/spdm_requester_lib/libspdm_req_get_certificate.c#L148-L150 https://github.com/DMTF/libspdm/blob/743f1db79a7c3fcf7f1784546e8fe0f20e0cc95a/library/spdm_requester_lib/libspdm_req_get_certificate.c#L64-L71

[Zhiqiang520]

This seems a new feature request.