Make syntect fancy

[cuviper]

This switches syntect from onig to fancy-regex for a pure Rust implementation of regular expressions.

It's also worth noting that onig's underlying oniguruma library says "This project ended on April 24, 2025", with its repo archived.

[google-cla[bot]]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[cuviper]

I don't know that I care to deal with a CLA for such a small change. I welcome anyone else to recreate this, which should be trivial even without looking at my commit.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 85.68%. Comparing base (886f15e) to head (16df8c1). Report is 15 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #265      +/-   ##
==========================================
+ Coverage   84.74%   85.68%   +0.93%     
==========================================
  Files          15       17       +2     
  Lines        3377     3674     +297     
  Branches     3377     3674     +297     
==========================================
+ Hits         2862     3148     +286     
- Misses        413      423      +10     
- Partials      102      103       +1     

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

:rocket: New features to boost your workflow:

• :snowflake: Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[mgeisler]

I don't know that I care to deal with a CLA for such a small change. I welcome anyone else to recreate this, which should be trivial even without looking at my commit.

Yeah, I understand completely! Sorry for the speed bump, it's a Google-wide policy to require an explicit signoff via the CLA.

I'll recreate it like you suggest. Thanks for the PR!

[mgeisler]

#267 should do the same, thanks again!