ParquetSharp 21.0.0

What's Changed

• Add sorting columns by @iksarfo in #536
• Upgrade C++ Arrow to 21.0.0 by @adamreeve in #548
• Allow specifying the native allocator in code by @adamreeve in #557

New Contributors

• @iksarfo made their first contribution in #536

Full Changelog: 20.0.0...21.0.0