Request to change anyhow to thiserror (or custom error) in grit-pattern-matcher

[ematipico]

Mostly because anyhow is meant for application code, and this forces downstream dependencies (Biome for example) to use anyhow to import the types and correctly handle the errors.

I wonder if you're open to changing this for a custom error or us the library thiserror. I am happy to send a PR too.

[morgante]

This has been on the back of my mind for a while, so definitely happy to change and would certainly appreciate a PR to move the core library crates over to thiserror.