Refactor save_vote function to use a lock for thread safety

main.py

@@ -68,13 +68,14 @@ app = FastAPI(lifespan=lifespan)
 
 
 def save_vote(vote_entry):
-    with open(VOTES_FILE, "a") as file:
-        date_time = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
-        vote_entry["timestamp"] = date_time
-        file.write(
-            json.dumps(vote_entry) + "\n"
-        )  # Add a newline character after writing each entry
-    logger.info(f"Vote saved: {vote_entry}")
+    with scheduler.lock:
+        with open(VOTES_FILE, "a") as file:
+            date_time = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+            vote_entry["timestamp"] = date_time
+            file.write(
+                json.dumps(vote_entry) + "\n"
+            )  # Add a newline character after writing each entry
+        logger.info(f"Vote saved: {vote_entry}")
 
 
 @app.get("/", include_in_schema=False)