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/resource.robot b/lib/resource.robot
index 49ddc4c..c12f52a 100755
--- a/lib/resource.robot
+++ b/lib/resource.robot
@@ -184,14 +184,14 @@
 Get Inventory Schema
     [Documentation]  Get inventory schema.
     [Arguments]    ${machine}
-    [Return]    &{INVENTORY}[${machine}]
+    RETURN    &{INVENTORY}[${machine}]
 
 Get Inventory Items Schema
     [Documentation]  Get inventory items schema.
     [Arguments]    ${machine}
-    [Return]    &{INVENTORY_ITEMS}[${machine}]
+    RETURN    &{INVENTORY_ITEMS}[${machine}]
 
 Get Sensor Schema
     [Documentation]  Get sensors schema.
     [Arguments]    ${machine}
-    [Return]    &{SENSORS}[${machine}]
+    RETURN    &{SENSORS}[${machine}]