Error creating cron job for Python script on Railway

Question

I'm trying to run a Python script on Railway.app, every 30 seconds, but it's not working. I tried with the codes below inside my project, but it seems to me that there is something wrong that doesn't work well. The main.py file runs normally once, but the cron function every 30 seconds is not working.

railway.json:

{
  "$schema": "https://railway.app/railway.schema.json",
  "build": {
    "builder": "NIXPACKS"
  },
  "deploy": {
    "startCommand": "uvicorn main:app --host 0.0.0.0 --port $PORT",
    "restartPolicyType": "ON_FAILURE",
    "restartPolicyMaxRetries": 10
  },
  "cron": {
    "job": "*/30 * * * * *",
    "command": "/bin/bash $APP_PATH/cron.sh"
  }
}

pyproject.toml:

[tool.poetry]
name = "railway-fastapi-template"
version = "0.1.0"
description = "This example starts up a FastAPI server"
authors = ["DeviousLab <deviouslab@gmail.com>"]
license = "MIT"

[tool.poetry.dependencies]
python = "^3.10"
fastapi = "^0.80.0"
uvicorn = "^0.18.3"

[tool.poetry.dev-dependencies]

[build-system]
requires = ["poetry-core>=1.0.0"]
build-backend = "poetry.core.masonry.api"

cron.sh

cd /app

python main.py

main.py:

from fastapi import FastAPI
from pydantic import BaseModel
import datetime

hora = datetime.datetime.now()

string_hora = "Executando o script em: " + str(hora)

app = FastAPI()

class Msg(BaseModel):
    msg: str

@app.get("/")
async def root():
    return {"message": f"{string_hora}"}