Pitchfork doesn't have a public json schema available so I put this one together, feel free to use this or suggest changes.
To add this schema to your pitchfork.toml use this syntax and url in the first line of the file:
#:schema https://gist.githubusercontent.com/wesleycoder/96af12e8fb9aeb0963ba66a449fe675e/raw/pitchfork.schema.json
# ... the rest of your file