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/lib/bmc_ipv6_utils.robot b/lib/bmc_ipv6_utils.robot
index 1d20c71..be26b4b 100644
--- a/lib/bmc_ipv6_utils.robot
+++ b/lib/bmc_ipv6_utils.robot
@@ -37,7 +37,7 @@
       Append To List  ${ipv6_data}  ${ip_n_prefix}
     END
 
-    [Return]  ${ipv6_data}
+    RETURN  ${ipv6_data}
 
 
 Verify IPv6 On BMC
@@ -86,4 +86,4 @@
     ${cmd_output}  ${stderr}  ${rc}=  BMC Execute Command
     ...  /sbin/ip -6 route
 
-    [Return]  ${cmd_output}
+    RETURN  ${cmd_output}