ci: Fix Schema Linting workflow

[justlevine]

What

Fixes the diffing the graphql schema.

Why

Related Issue(s):

How

@todo

Testing Instructions

Screenshots

Additional Info

Checklist

• I have read the Contribution Guidelines.
• My code is tested to the best of my abilities.
• My code passes all lints (PHPCS, PHPStan, ESLint, etc).
• My code has detailed inline documentation.
• I have added unit tests to verify the code works as intended.
• I have updated the project documentation accordingly.