[RFC] Find a way to make Remote Caching work when building PRs sent from a fork of a GitHub repo

[steveluscher]

Which project is this feature idea for?

Turborepo

Describe the feature you'd like to request

When a community member sends my repo a pull request from their own fork, I have a workflow that builds their submitted code with Turborepo. Under these conditions, remote caching does not work.

1. GitHub does not vend secret tokens to workflows that run on PRs from community forks. This is a security feature.
2. Turborepo fails to find TURBO_TOKEN in such cases therefore fails to access the remote cache.

Describe the solution you'd like

A technique for caching and recovering cached artifacts in workflows that run Turborepo on PRs from community forks on GitHub.

Describe alternatives you've considered

1. Hardcoding the TURBO_TOKEN into the workflow rather than using environment variables, thereby leaking it to the public.
2. Uploading source code to an artifact cache in the PR that runs on the workflow, and then having a follow-on workflow with escalated privileges download those artifacts and build the code with Turborepo.