How to configure GithubAction to assume role to access my CodeBuild Project

I am using GithHub Actions with CodeBuild,when I run GitHub Actions,I am getting error message CodeBuild project name can not be found.The issue is that my codebuild project is in my assumed role(sandbox_role) but github action is looking for the project in the root account that i configured as environment variable in github secret.How can I configure my GitHub Action workflows to first connect to the root then from there assume sandbox_role to get my codebuild project?below is my code sample.I am using terragrunt/terraform code to provision my environment.

​name:'GitHub Actions For CodeBuild'

​on:
​pull_request:
​branches:
​- staging
​jobs:
​CodeBuild:
​name:‘Build’
​runs-on:ubuntu-latest

​steps:
​-name:‘checkout’
​uses:actions/checkout@v2

    ​-name:configure AWS credentials
     ​uses:aws-actions/configure-aws-credentials@v1
     ​with:
       ​aws-access-key-id: ${{secrets.AWS_ACCESS_KEY_ID}}
       ​aws-secret-access-key: ${{secrets.AWS_SECRET_ACCESS_KEY }}
       ​aws-region: us-east-1
   ​-name:Run CodeBuild
    ​uses: aws-actions/aws-codebuild-run-build@v1
    ​with:
      ​project-name: CodeBuild
      ​buildspec-override: staging/buildspec.yml
      ​env-vars-for-codebuild: |
       ​TF_INPUT,
       ​AWS_ACCESS_KEY_ID,
       ​AWS_SECRET_ACCESS_KEY,
       ​AWS_REGION,


​env:
​TF_INPUT: false
​ AWS_ACCESS_KEY_ID: ${{secrets.AWS_ACCESS_KEY_ID}}
​AWS_SECRET_ACCESS_KEY: ${{secrets.AWS_SECRET_ACCESS_KEY }}
​AWS_REGION: us-east-1