libsquish Release v1.15.1

What's Changed

New Features

• Overhaul CMake scripts to employ Modern CMake practices by @oblivioncth in #1
• Add CI/CD via Actions by @oblivioncth in #2

Other Changes

• CI: Install libpng on Windows for Png target by @oblivioncth in #3

New Contributors

• @oblivioncth made their first contribution in #1

Full Changelog: https://github.com/oblivioncth/libsquish/commits/v1.15.1