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/network/test_vlan_network.robot b/network/test_vlan_network.robot
index 57972c3..8feb2fb 100644
--- a/network/test_vlan_network.robot
+++ b/network/test_vlan_network.robot
@@ -335,7 +335,7 @@
     ...  /sbin/ip addr | grep @eth0 | cut -f1 -d@ | cut -f2 -d.
     ${vlan_ids}=  Split String  ${vlan_ids}
 
-    [Return]  @{vlan_ids}
+    RETURN  @{vlan_ids}
 
 
 Get VLAN URI For IP
@@ -362,7 +362,7 @@
     ${uris}=  Get Dictionary Keys  ${vlan_record}
     Return From Keyword If  @{uris} == @{EMPTY}
 
-    [Return]  ${uris[${0}]}
+    RETURN  ${uris[${0}]}
 
 
 Verify Existence Of VLAN