How can I execute a SQL Script in Heroku Postgres using yml file?

Question

Today I have a .NET 6 application that uses the Code First approach to the database, where I generate migrations and put my code on GitHub.

I use GitHub Actions to deploy my application using a .yml file:

# Docs for the Azure Web Apps Deploy action: https://github.com/Azure/webapps-deploy
# More GitHub Actions for Azure: https://github.com/Azure/actions

name: Build and deploy ASP.Net Core app to Azure Web App - petshop-dogstyle-api

on:
  push:
    branches:
      - master

jobs:
  build-and-deploy:
    runs-on: windows-latest
    environment:
      name: 'Production'
      url: ${{ steps.deploy-to-webapp.outputs.webapp-url }}

    steps:
      - uses: actions/checkout@v2

      - name: Set up .NET Core
        uses: actions/setup-dotnet@v1
        with:
          dotnet-version: '6.0.x'
          include-prerelease: true

      - name: Build with dotnet
        run: dotnet build --configuration Release
        
      - name: Install EF Tool
        run: |
            dotnet new tool-manifest
            dotnet tool install dotnet-ef

      - name: dotnet publish
        run: dotnet publish -c Release -o ${{env.DOTNET_ROOT}}/myapp
        
      - name: Generate scripts
        run: dotnet ef migrations script --output ${{env.DOTNET_ROOT}}/sql/migration-script.sql --idempotent --project PetShop.API

      - name: Azure SQL Deploy
        uses: Azure/[email protected]
        with:
          # Name of the Azure SQL Server name, like dotnetthoughts.database.windows.net.
          server-name: tcp:petshop-sqlserver.database.windows.net
          # The connection string, including authentication information, for the Azure SQL Server database.
          connection-string: ${{ secrets.CONNECTION_STRING }}
          # Path to SQL script file to deploy
          sql-file: ${{env.DOTNET_ROOT}}/sql/migration-script.sql
          
      - name: Run Azure webapp deploy action using publish profile credentials
        uses: azure/webapps-deploy@v2
        with:
          app-name: 'petshop-dogstyle-api'
          slot-name: 'Production'
          publish-profile: ${{ secrets.AZUREAPPSERVICE_PUBLISHPROFILE_394CE20008F94B01AF05CA0673305854 }}
          package: ${{env.DOTNET_ROOT}}/myapp

But because Azure doesn't have the option to have a free database, I'm migrating it to Heroku and using Postgres.

But I don't know how to run my migrations script on Heroku. How can I do this?