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_bmc_dhcp_conf.robot b/network/test_bmc_dhcp_conf.robot
index d44dbb8..06e341b 100644
--- a/network/test_bmc_dhcp_conf.robot
+++ b/network/test_bmc_dhcp_conf.robot
@@ -89,7 +89,7 @@
     ${resp}=  Redfish.Get  ${REDFISH_NW_ETH_IFACE}${ethernet_interface}
 
     @{network_configurations}=  Get From Dictionary  ${resp.dict}  IPv4StaticAddresses
-    [Return]  @{network_configurations}
+    RETURN  @{network_configurations}
 
 Apply Ethernet Config
     [Documentation]  Set the given Ethernet config property.