Adds support for Crystal 1.13.x

What's Changed

• Updated to work with crystal 1.2 and Bumped version number to v0.9.3. by @elorest in #5
• Update for Crystal 1.13 by @xendk in #6

New Contributors

• @elorest made their first contribution in #5
• @xendk made their first contribution in #6

Full Changelog: v0.9.3...v0.9.4