Change ping endpoint for validating api key (#1956)

mem0/client/main.py

@@ -94,7 +94,7 @@ class MemoryClient:
     def _validate_api_key(self):
         """Validate the API key by making a test request."""
         try:
-            response = self.client.get("/v1/memories/", params={"user_id": "test"})
+            response = self.client.get("/v1/ping/")
             response.raise_for_status()
         except httpx.HTTPStatusError:
             raise ValueError("Invalid API Key. Please get a valid API Key from https://app.mem0.ai")