Github Action with two schemas without endpoint

[Amnesthesia]

Is your feature request related to a problem? Please describe.

We use react-native, where we have a schema in a separate repository. We'd like to be able to check whether a PR to our other repository is compatible with the schema in our react-native repository

Describe the solution you'd like

Support comparing a local schema file with another local schema file, or schema files in separate repositories

Describe alternatives you've considered

• Attempt to host schema file on S3 (403 because if you specify endpoint, it seems to try to use POST anyway, 405 if the bucket is public)

[osnoser1-slalom]

I would love to use this, I moved a schema to a different location and I can't specify the destination path in the PR where I run the action