stop frequent downloading of dataset

app.py

@@ -54,7 +54,9 @@ def bar_plot(df):
     st.pyplot(fig)
 
 if __name__ == '__main__':
-    os.system('python download_dataset.py')
+    if not os.path.exists('/home/user/app/aesdd.zip'):
+        os.system('python download_dataset.py')
+
     test = load_data()
 
     config, processor, model, device = cache_model()