Bump pandas from 1.2.0 to 1.2.1

Bumps [pandas](https://github.com/pandas-dev/pandas) from 1.2.0 to 1.2.1.
- [Release notes](https://github.com/pandas-dev/pandas/releases)
- [Changelog](https://github.com/pandas-dev/pandas/blob/master/RELEASE.md)
- [Commits](https://github.com/pandas-dev/pandas/compare/v1.2.0...v1.2.1)