Replaced  deprecated API used

Change-Id: Ia9ac743ba3d6516edb872b3b4667b9ca201a36c0

Changes:

       - Replace deprecated API in 'Download BMC Dump'.

Tested:

       - Ran the related testcases from sandbox successfully.

Change-Id: Iccf953b7ceefe228520b4906388f9cdb782dbcee
Signed-off-by: manashsarma <manashsarma@in.ibm.com>
diff --git a/redfish/managers/test_bmc_dumps.robot b/redfish/managers/test_bmc_dumps.robot
index 309b72e..66f9700 100644
--- a/redfish/managers/test_bmc_dumps.robot
+++ b/redfish/managers/test_bmc_dumps.robot
@@ -514,7 +514,7 @@
     Initialize OpenBMC
     ${headers}=  Create Dictionary  Content-Type=application/octet-stream  X-Auth-Token=${XAUTH_TOKEN}
 
-    ${ret}=  Get Request  openbmc  /redfish/v1/Managers/bmc/LogServices/Dump/Entries/${dump_id}/attachment  headers=${headers}
+    ${ret}=  GET On Session  openbmc  /redfish/v1/Managers/bmc/LogServices/Dump/Entries/${dump_id}/attachment  headers=${headers}
 
     Should Be Equal As Numbers  ${ret.status_code}  200