Deploying Node.js app to Heroku with error H10 stating that "/tmp/start-d846bb8e.sh: 1: nodemon: not found"

So I've been trying to deploy my app with Heroku, and it runs locally perfectly fine, but I keep running into the same H10 error below:

2022-09-15T02:57:14.484472+00:00 heroku[web.1]: Starting process with command `npm start`
2022-09-15T02:57:17.725863+00:00 app[web.1]: 
2022-09-15T02:57:17.725906+00:00 app[web.1]: > node-sso-example-app@1.0.0 start
2022-09-15T02:57:17.725912+00:00 app[web.1]: > nodemon index.js
2022-09-15T02:57:17.725915+00:00 app[web.1]: 
2022-09-15T02:57:17.731558+00:00 app[web.1]: /tmp/start-d846bb8e.sh: 1: nodemon: not found
2022-09-15T02:57:17.847830+00:00 heroku[web.1]: Process exited with status 127
2022-09-15T02:57:17.916430+00:00 heroku[web.1]: State changed from starting to crashed
2022-09-15T02:57:19.230286+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=will-dersh.herokuapp.com request_id=9e07b48e-dcd7-42eb-b6bc-d9d7e138b15a fwd="108.67.29.121" dyno= connect= service= status=503 bytes= protocol=https
2022-09-15T02:57:19.499659+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=will-dersh.herokuapp.com request_id=f7501cb9-60c7-457d-97ed-63cffdfe872f fwd="108.67.29.121" dyno= connect= service= status=503 bytes= protocol=https

Here's my index.js file:

 import express from 'express'
    import 'dotenv/config'
    import router from './routes/index.js'
    import morgan from 'morgan'
    
    const app = express()
    
    app.use('/public', express.static('public'))
    
    app.use(express.urlencoded({ extended: false }))
    
    app.use(express.json())
    
    app.use(morgan('dev'))
    
    app.use('/', router)
    
    app.listen(process.env.PORT || 8000, function(){
        console.log("Express server listening on port %d in %s mode", this.address().port, app.settings.env);
    });

Here's the package.json:

{
  "name": "node-sso-example-app",
  "version": "1.0.0",
  "description": "Example Node.js SSO App using WorkOS",
  "main": "index.js",
  "type": "module",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "nodemon index.js"
  },
  "author": "WorkOS",
  "dependencies": {
    "@workos-inc/node": "^2.11.0",
    "cookie-parser": "^1.4.6",
    "dotenv": "^16.0.1",
    "ejs": "^3.1.8",
    "express": "^4.18.1",
    "express-session": "^1.17.2",
    "http-errors": "~1.6.3",
    "morgan": "^1.10.0",
    "router": "^1.3.7"
  },
  "devDependencies": {
    "nodemon": "^2.0.19"
  }
}

And if it helps, here is my Procfile:

web:node index.js

I'm not really sure where I've gone wrong so any help would be appreciated!