upgrade to node20 (#14)

Set SPECTRAL_DSN environment from JS instead of end-user workflow file (

#12)

* Update index.js

* Update README.md

* Update main.yml

* Update README.md

* Update README.md

* Update CI.yml

* Update main.yml

* Update CI.yml

update ci and readme to use the new action version

Merge pull request #4 from SpectralOps/install-and-run

Install and run spectral in a single command

initial commit