feat: add train model function to be called from app.py

psy.py

@@ -50,7 +50,10 @@ trainer = Trainer(
     compute_metrics=compute_metrics,
 )
 
+
+def train_model()
+    trainer.train()
 # Finally, fine-tune!
 if __name__ == "__main__":
-    trainer.train()
+    train_model()