I want to use the GCP transcoder on my vercel project but the transcoder authorization uses ADC which looks for a service-key.json file. I can't publish this file to Vercel so I have it in an env variable which works for other GCP functions. However, it seems like the ADC for the transcoder is automatic so it doesn't look through the env variables. I half-heartedly tried using OIDC but was having trouble with getting step 8 of the setup. Any help would be appreciated.