fix: properly shutdown telemetry aiohttp sessions to prevent ImportError during Python shutdown

- Change atexit handler from flush() to shutdown() in telemetry/__init__.py
- This ensures PostHog aiohttp sessions are properly closed before Python shutdown
- Prevents ''ImportError: sys.meta_path is None, Python is likely shutting down'' error
- Maintains backward compatibility with existing functionality

Fixes #963

Co-authored-by: Mervin Praison <MervinPraison@users.noreply.github.com>

Author: github-actions[bot]

src/praisonai-agents/praisonaiagents/telemetry/__init__.py

@@ -65,8 +65,8 @@ def _ensure_atexit():
     ])
 
     if not telemetry_disabled:
-        # Register atexit handler to flush telemetry on exit
-        atexit.register(lambda: get_telemetry().flush())
+        # Register atexit handler to properly shutdown telemetry on exit
+        atexit.register(lambda: get_telemetry().shutdown())
         _atexit_registered = True
 
 def _initialize_telemetry():