Azure App Service Deploy - include files from grunt build in deployment package

Question

Using Azure DevOps pipelines, I've got a task to deploy to an Azure app service, which looks like this in my YAML file:

 - task: AzureRmWebAppDeployment@4
  inputs:
    ConnectionType: 'AzureRM'
    appType: 'webApp'
 
    packageForLinux: '$(build.artifactStagingDirectory)/Project.zip'
    azureSubscription: ''
    WebAppName:  ''
    ResourceGroupName: ''
    deployToSlotOrASE: true
    SlotName: 'production'
    enableCustomDeployment: true
    RemoveAdditionalFilesFlag: false

The project.zip file is built with a standard msbuild task.

- task: VSBuild@1
  inputs:
    solution: '$(solution)'
    msbuildArgs: '/p:DeployOnBuild=true /p:WebPublishMethod=Package /p:PackageAsSingleFile=true /p:SkipInvalidConfigurations=true /p:PackageLocation="$(build.artifactStagingDirectory)"'
    platform: '$(buildPlatform)'
    configuration: '$(buildConfiguration)'
    clean: true
    

However, In the Project.zip file I want to include some files that have been built from a grunt build pipeline which looks like the following:

- task: Grunt@0
  inputs:
    gruntFile: 'Project\gui\styleguide\gruntfile.js'
    targets: 
    gruntCli: 'node_modules/grunt-cli/bin/grunt'

How can I include the assets built from grunt, into the package that is deployed to my Azure app?