Missing CI and semver check resulted in a breaking change

[nyurik]

Hi, thanks for the hard work on doing this!

This repo badly needs a proper CI (preferably github actions for convenience), and as part of it it should include semver compatibility check. Simply add - uses: obi1kenobi/cargo-semver-checks-action@v2 step into the github action, and it will do all the hard work.

Otherwise users of cargo install <project-that-uses-freetype-rs> will break like here