In spec only S3 old key dropped before verify new key operation

[OuyangHang33]

Ref: #7

spdm-rs/spdmlib/src/responder/key_update_rsp.rs

Lines 71 to 76 in acf74d7

	SpdmKeyUpdateOperation::SpdmUpdateAllKeys => {
	let _ = session.create_data_secret_update(spdm_version_sel, true, true);
	let _ = session.activate_data_secret_update(spdm_version_sel, true, true, true);
	}
	SpdmKeyUpdateOperation::SpdmVerifyNewKey => {
	let _ = session.activate_data_secret_update(spdm_version_sel, true, false, true);