Update project

[ctreffs]

Description

• Fix issue Cannot find TextureTypeToString in scope AiTextureType.swift #11 - by dropping AiTextureType conformance to CustomStringConvertible.
• Remove custom pkg-config files for mac - libassimp.5.2.4 has working support
• Update tests
• Update mint dependencies
• Update CI dependencies
• Upgrade CI for current macOS and Linux versions

Checklist

• I've read the Contribution Guidelines
• I've followed the coding style of the rest of the project.
• I've added tests covering all new code paths my change adds to the project (to the extent possible).
• I've added benchmarks covering new functionality (if appropriate).
• I've verified that my change does not break any existing tests or introduce unexpected benchmark regressions.
• I've updated the documentation (if appropriate).