Robot Framework 7.0 changes

Update robot code syntax overall in the repo

Changes:
   - Update the requirement.txt package version for robot
   - The '[Return]' setting is deprecated.
      Use the 'RETURN' statement instead.
   - Singular section headers like '*** Test Case ***'
     are deprecated. Use plural format like
     '*** Test Cases ***' instead.
   - Singular section headers like '*** Variable ***'
     are deprecated

Tested:
   - Ran from sandbox with the version
     $ robot --version
     Robot Framework 7.0 (Python 3.10.12 on linux)

     and also tested on latest python version

     Robot Framework 7.0 (Python 3.11.9 on linux)

Change-Id: I54e85f9d799556c63b9a39f79483f83e9b980768
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/redfish/systems/test_powersubsystem_settings.robot b/redfish/systems/test_powersubsystem_settings.robot
index bb45fd0..c38dbe1 100755
--- a/redfish/systems/test_powersubsystem_settings.robot
+++ b/redfish/systems/test_powersubsystem_settings.robot
@@ -121,7 +121,7 @@
     # {'@odata.id': '/redfish/v1/Chassis/chassis/PowerSubsystem/PowerSupplies/powersupply1'}
     # {'@odata.id': '/redfish/v1/Chassis/chassis/PowerSubsystem/PowerSupplies/powersupply2'}
     # {'@odata.id': '/redfish/v1/Chassis/chassis/PowerSubsystem/PowerSupplies/powersupply3'}
-    [Return]  ${total_num_powersupplies}
+    RETURN  ${total_num_powersupplies}
 
 
 Set and Verify Power Mode Switches