Improvements
- Add support for Python 3.10 (504).
- The csv, xls, and xlsx formats gained support for the `skip_lines` keyword
argument for their `import_set()` method to be able to skip the nth first
lines of a read file (497).
Bugfixes
- Avoided mutable parameter defaults (494).
- Specify build backend for editable installs (501).
- Doubled sample size passed to `csv.Sniffer()` in `_csv.detect()` (503).