Using Github Private NPM package with the npm buildpack on digital ocean app platform

Hello! I am currently creating a CICD pipeline for our platform and am struggling with the automated builds for our front end.

It is a simple npm-based setup. We have a client library for our backend, which is privately stored in our GitHub organization. I modified our .npmrc file in our frontend to look as:

@<our organization>:registry=https://npm.pkg.github.com
//npm.pkg.github.com/:_authToken=${GITHUB_TOKEN}

I then created an environment variable via Terraform for the static site:

env {
        key = "GITHUB_TOKEN"
        value = "var.github_token"
        scope = "BUILD_TIME"
        type = "SECRET"
      }

Now, when I trigger a deployment, I get the error:

npm ERR! code E401
npm ERR! 401 Unauthorized - GET <redacted> - authentication token not provided

Everything worked fine when I tested this locally with npm ci after setting the environment variable.

Earlier in the build logs, it even states that it uses the GITHUB_TOKEN environment variable, I can only imagine that the node.js buildpack does not use it.

Any hint would be appreciated!