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/certificate_utils.robot b/lib/certificate_utils.robot
index e8faf5d..56046a3 100755
--- a/lib/certificate_utils.robot
+++ b/lib/certificate_utils.robot
@@ -41,7 +41,7 @@
 
     Delete All Sessions
 
-    [Return]  ${cert_id}
+    RETURN  ${cert_id}
 
 
 Get Certificate Content From BMC Via Openssl
@@ -56,7 +56,7 @@
     ${result}=  Fetch From Left
     ...  ${output}  -----END CERTIFICATE-----
     ${result}=  Fetch From Right  ${result}  -----BEGIN CERTIFICATE-----
-    [Return]  ${result}
+    RETURN  ${result}
 
 
 Get Certificate File Content From BMC
@@ -69,7 +69,7 @@
     ${certificate}  ${stderr}  ${rc}=  Run Keyword If  '${cert_type}' == 'Client'
     ...    BMC Execute Command  cat /etc/nslcd/certs/cert.pem
 
-    [Return]  ${certificate}
+    RETURN  ${certificate}
 
 
 Generate Certificate File Via Openssl
@@ -127,7 +127,7 @@
     ${cert_name}=  Catenate  SEPARATOR=  ${random_name}  .pem
     Create File  ${cert_dir_name}/${cert_name}  ${cert_data}
 
-    [Return]  ${EXECDIR}${/}${cert_dir_name}${/}${cert_name}
+    RETURN  ${EXECDIR}${/}${cert_dir_name}${/}${cert_name}
 
 
 Get Certificate Content From File
@@ -140,7 +140,7 @@
     ${file_content}=  OperatingSystem.Get File  ${cert_file_path}
     ${result}=  Fetch From Left  ${file_content}  -----END CERTIFICATE-----
     ${result}=  Fetch From Right  ${result}  -----BEGIN CERTIFICATE-----
-    [Return]  ${result}
+    RETURN  ${result}
 
 
 Check If Openssl Tool Exist
@@ -290,7 +290,7 @@
     ...  ${certificate_uri}/${cert_id}  CertificateString
 
     Run Keyword If  '${expected_status}' == 'ok'  Should Contain  ${cert_file_content}  ${bmc_cert_content}
-    [Return]  ${cert_id}
+    RETURN  ${cert_id}
 
 
 Modify BMC Date