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/openpower/test_timed_power_on.robot b/openpower/test_timed_power_on.robot
index 2f24511..05167e8 100644
--- a/openpower/test_timed_power_on.robot
+++ b/openpower/test_timed_power_on.robot
@@ -137,7 +137,7 @@
     ${time_set}=  Evaluate  ${current_bmc_time[0]} + ${TIMER_POWER_ON}
     BMC Execute Command  ${CMD_SET_TPO_TIME} ${time_set}
 
-    [Return]  ${time_set}
+    RETURN  ${time_set}
 
 
 Get Time Power ON Value
@@ -148,4 +148,4 @@
     ${return_value}=  Evaluate  ${return_value}[1]
 
     # BMC command returns integer value.
-    [Return]  ${return_value}
+    RETURN  ${return_value}