fix: TypeError from journal_name (#3614)

fix: TypeError from jounral_name

Author: mkundu1

src/ansys/fluent/core/services/app_utilities.py

@@ -342,7 +342,8 @@ def get_app_mode(self) -> Enum:
     def start_python_journal(self, journal_name: str | None = None) -> int:
         """Start python journal."""
         request = AppUtilitiesProtoModule.StartPythonJournalRequest()
-        request.journal_name = journal_name
+        if journal_name:
+            request.journal_name = journal_name
         response = self.service.start_python_journal(request)
         return response.journal_id