SWDEV-478077 - logging.warn used instead of logging.warning

- logging.warn() is deprecated in favour of logging.warning()
- for some reason, this is the only place in all of rocm_smi.py
	that uses logging.warn() as pointed out on github
	https://github.com/ROCm/rocm_smi_lib/issues/187

Change-Id: Ie1e4a0ea16b996fbed2e902c8edfe68087a5a5fa

python_smi_tools/rocm_smi.py

@@ -4287,7 +4287,7 @@ if __name__ == '__main__':
             if not JSON_DATA['card' + str(device)]:
                 JSON_DATA.pop('card' + str(device))
         if not JSON_DATA:
-            logging.warn("No JSON data to report")
+            logging.warning("No JSON data to report")
             sys.exit(RETCODE)
 
         if not args.csv: